This will be Jake Peavy’s first full season with the Chicago White Sox, and it’s well documented that his new home ballpark, U.S. Cellular, inflates home run totals while his former park, Petco Park, suppresses them quite a bit. So we should expect Peavy to give up more home runs — but how many more?

One way to answer the question is to look at the home run per fly ball rates, or HR/FB, of each park relative to Peavy’s fly-ball numbers. We know fly-ball rates normalize more quickly than simple home run rates, and pitchers generally allow homers on about 11 percent of their fly balls. So this approach allows us to take a pretty nuanced look at the problem.

A study by Dan Turkenkopf of The Hardball Times shows us that “The Cell” and Petco have HR/FB indices of 118 and 75, respectively. What that means is that if you multiply those numbers by .11 (percentage of all fly balls that become homers), you discover that about 13 percent of fly balls become homers in Chicago, versus only about 8.25 percent in San Diego.

Before we see how that affects Peavy, let’s look at his record with the Padres.

Peavy away from Petco Park
Season	HR	FB	HR/FB
2004	9	81	11.1%
2005	6	82	7.3%
2006	11	110	10.0%
2007	8	102	7.8%
2008	13	75	17.3%
2009	3	27	7.9%
Total	50	477	10.5%

Peavy at Petco Park
Season	HR	FB	HR/FB
2004	4	81	4.9%
2005	12	105	11.4%
2006	12	130	9.2%
2007	5	121	4.1%
2008	4	100	4.0%
2009	4	53	8.1%
Total	41	590	6.9%

We see a couple of things here. First, Peavy benefited from Petco’s home-run suppression, as seen by his lower HR/FB rate. Also, he gave up a greater number of fly balls at Petco. The latter is due to a significant imbalance in his innings-pitched home/away splits between 2004 and 2009: 591 innings at Petco versus only 458 innings away.

Therefore, we need to figure out how many fly balls Peavy allows on average. Since 2004, he’s allowed 477 flies in 458 away innings (1.04 FB/IP) and 590 flies in 591 home innings (1.00 FB/IP). Basically, he allows almost exactly one fly ball per inning.

If we project Peavy to throw 200 innings, split equally between The Cell and opposing parks, we get something like this:

Home: 100 IP = 100 FB at 13% HR/FB = 13 HR (1.17 HR/9)
Away: 100 IP = 100 FB at 11% HR/FB = 11 HR (0.99 HR/9)
Total: 200 IP = 200 FB = 24 HR (1.08 HR/9)

Of course, this isn’t a stone-cold lock. There are other variables to consider, such as the fact that he is moving to a league with a designated hitter, but 24 is a legitimate estimate.

How does that compare to his usual numbers? Well, since 2004, when Petco opened, Peavy has posted a 0.77 HR/9 rate, meaning that, in any given 200 innings, he’d allow about 17 home runs.

So over 200 innings, Peavy should give up around seven more homers than he did with the Padres. That’s enough to give his ERA a bit of a bump but not enough to prevent him from remaining an elite pitcher.

As expected, the White Sox will continue to use Bobby Jenks as their closer this year, despite having a superior bullpen arm in Matt Thornton. For the past two seasons, Thornton has been a buried treasure, posting better numbers than the Southside’s closer. For that matter, his FIP (a defense-independent measure of ability) has been better than many other team’s closers.

The White Sox aren’t the only team that does not have their best relief pitcher throwing in the ninth. Kevin Jepsen of the Angels is a better pitcher than Brian Fuentes, and the Mariners’ Brandon League could very well be better than David Aardsma. In one extreme case, the 2007 Indians continued to use Joe Borowski as their closer despite his bloated 5.07 ERA, while they reserved Rafael Betancourt for the eighth inning. Betancourt posted a minuscule 1.47 ERA and 2.22 FIP that year.

For fans that follow these teams, it’s frustrating to see the manager continue to go to the well with these “proven closers” while neglecting to give these elite arms their fair shot at saving games. Well, the aggravation of fans aimed towards the manager in most cases is unnecessary. No, they aren’t using their assets in the best possible way, but the impact isn’t a big as you might think.

With the help of Tom Tango, FanGraphs provides a stat that measures the magnitude of every game situation called Leverage Index, or LI for short. Here’s the gist, and this takes us back to what Sky shared about the Twins loss of Joe Nathan earlier in the month:

-The average situation (think of the starting pitcher’s role) has an LI of 1.
-Closers appear in situations with an average LI of about 1.8, meaning runs allowed by closers are a little less than twice as damaging as the average run.
-Set-up men will see LIs in the 1.3 to 1.6 range.

So while closers on average pitch in more crucial situations, the set-up man pitches in some pretty important situations as well, and often more frequently.

For a practical example we’ll use Jenks and Thornton of 2009 White Sox. What happens if we go back into 2009, only with Jenks and Thornton swapping roles? Jenks posted a FIP of 4.47 over 53 1/3 innings, with an average LI of 1.9. This made him good for 4 runs above replacement level, or about half a win. Thorton threw 72 1/3 innings, with a 2.47 FIP, with an average LI of 1.5. That made Thornton good for 26 runs above replacement level. If you give Thornton’s innings and leverage to Jenks, and vice versa, the difference in runs above replacement comes out to be about a single run. That’s all.

Part of the extra value that a set-up man has is he isn’t restricted to just the ninth inning with a lead. Many non-save situations are crucial to a team’s chances of winning, and in fact, a lot of high leverage situations happen when a team is trailing by just one run — a situation where a manager will almost never use his closer, even though keeping the score close gives his team a chance for a come from behind victory.

Non-closer relievers can be extremely valuable in these middle innings, high leverage situations, so it’s not the end of the world if your team’s manager chooses to employ an inferior pitcher to close out games. Thornton, Jepsen, and League will provide plenty of value, even if they don’t rack up many saves.

Maybe you heard that some guy named Jason Heyward made the Atlanta Braves’ Opening Day roster. It could have something to do with the sound of the ball coming off his bat, which was a daily discussion at Champion Field in Orlando, Fla. Or maybe it was all those cars that Heyward dented with his devastating drives over the right-field wall.

But more likely, it had to do with how Heyward — despite being all of 20 years old — has dominated every minor league station and seems ready for the majors. While toying with minor league pitchers, he constantly showed his trademark patience — he had 105 walks to 138 career strikeouts, an elite strikeout-to-walk ratio for a young prospect. He also showed more power as he advanced, an excellent sign for his future.

There have been some recent prospects who came to the majors with similar pedigrees at this young age. But a quick scan of their debut seasons might be reason for pessimism regarding Heyward’s upcoming season.

Player	        AB	BA	OBP	SLG	HR	R	RBI	SB
Miguel Cabrera	314	.268	.325	.468	12	39	62	0
B.J. Upton	159	.258	.324	.409	4	19	12	4
Justin Upton	140	.221	.283	.364	2	17	11	2
Delmon Young	126	.317	.336	.476	3	16	10	2

Not quite the list that an Atlanta Braves fan would want to see. But this is why age factors so prominently in the appraisal of prospects — the fact that Miguel Cabrera could come up at age 20 and even put up a slightly above-average season at the plate meant that his future was bright. But if he put the same season up four years later, there would not have been much reason for excitement. So the fact that Heyward will create an entry for himself on this list is almost as important as his results.

But there are also reasons to expect better from Heyward. His minor league walk-to-strikeout ratio (0.76) is miles better than Miguel Cabrera’s decent 0.5 minor league number. His .190 career minor league ISO (slugging percentage minus batting aveage) is barely bested by Justin Upton’s .193 and Delmon Young’s .200. So to put Heyward’s skills in focus, relative to other recent young debuts, he’s got plate discipline better than Miguel Cabrera along with power comparable to Justin Upton.

Red Sox catcher Jason Varitek was an integral part of Boston’s championship teams of 2004 and 2007, but he’s pretty clearly in the decline phase of his career. The Red Sox are aware of this, given their trade for catcher Victor Martinez in 2009. But believe it or not, Varitek isn’t entirely useless, and this isn’t because of any “intangibles,” the “C” on his uniform, or the time he took a swing at A-Rod while keeping his catcher’s facemask on. Strictly by the numbers, Jason Varitek still has something to offer as a player.

In 2009, Varitek hit .209/.313/.390. And over the last three seasons he hit .229/.322/.390. Those are pretty dreadful lines. However, slugging catchers like Joe Mauer and Brian McCann are far from the norm. Last year, the average catcher hit .254/.321/.396. That means that Varitek’s hitting line is pretty much average for a backstop.

Wins Above Replacement (WAR) is useful for cases just like this. Since average major league players have substantial value, WAR uses a different baseline, combining offense, defense, and a positional adjustment to see how many wins over a freely available Triple-A talent (a “replacement player”) each player contributes given his playing time. Over a full season, 2 WAR is about average. According to FanGraphs, Varitek was worth 1.2 WAR in 2008 and 1.3 in 2009. What is a replacement level catcher? In similar playing time, Rays catcher Dioner Navarro was worth a -0.2 WAR in 2009. He “hit” .218/.261/.322 and ended up just barely below replacement level.

Varitek, who turned 38 years old is April, is best suited as a part-timer at this point, but he has a role to play for the Red Sox. Martinez hasn’t caught more than 100 games since 2007. It’s extremely rare for any team, even the Red Sox, to have an above-average player on the bench. And though Varitek is probably just a tick below average, that’s still very good for a back-up catcher. Boston looks to be in another tight race this season, and on the days when Martinez isn’t catching, they could do much worse than Varitek, who is still a perfectly useful big league backstop.

After a year in which three of their best players missed a major chunk of the season, the Mets needed some good news to kick off 2010. They’ve gotten some in the form of the performance of their best prospect, righthander Jenrry Mejia. After striking out more than a man per inning last season as the youngest player in the Eastern League (Double-A), the 20-year-old has been the talk of camp with his electric mid-90s fastball. He’s been so good, in fact, that the club is thinking of promoting him to the big leagues as a reliever. While he might thrive in that role, it would still be a bad decision.

Manager Jerry Manuel has pondered Mejia in the bullpen because he thinks he and Francsico Rodriguez will give the team a dynamic one-two combo to finish games. The problem is that Mejia still has a lot of development left. He admits his command issues, saying that he aims for the middle of the plate and hopes for the best. His slider also needs work, though he does feature an impressive changeup. As a reliever, these secondary pitches would not get the attention they need to improve.

The Mariners and Yankees should both provide cautionary tales for the Mets. Each tried to groom a young starter with ace potential, Brandon Morrow and Joba Chamberlain respectively, in the major league bullpen. While both performed well, they have also struggled in the transition back to the rotation. The Mariners ended up trading Morrow, while the Yankees have seemingly moved Chamberlain back to the bullpen once again.

What’s so bad about the bullpen? After all, both Morrow and Chamberlain have pitched well as relievers. Their teams, though, won’t realize maximum value. Starters affect a much greater portion of a team’s innings. If a team has 1450 IP in a season, a 200-inning starter covers 13.8 percent of the total time. A reliever who throws 70 innings affects just 4.8 percent of total innings. This shows up in Wins Above Replacement (WAR), too. Last year Barry Zito, who had had a 4.03 ERA in 192 innings, was worth 2.2 WAR, while Heath Bell, the NL saves leader, was worth 2.0 WAR. And if you don’t believe WAR, look at the free agent market, where the contracts given to top-flight starters typically dwarf those given to elite relievers.

The Mets might not have as strong a bullpen this year without Mejia, but by allowing him to properly develop in the minors they could see a greater return in the future. That’s not easy to stomach for fans who want to win today, nor is it an easy decision for Jerry Manuel and Omar Minaya whose jobs might be on the line, but it is the correct one for the future of the team. Considering the Mets haven’t featured a homegrown ace since Doc Gooden, you’d think they realize it would be foolish to stunt Mejia’s growth.

Ricky Nolasco was one of the biggest disappointments in baseball last year, posting a 5.06 ERA when he was expected to be a front-line starter for the Marlins. However, if you peruse the leaderboards at FanGraphs, you may notice that Nolasco actually pitched really well most of the time; his 3.28 xFIP (which stands for Fielder Independent Pitching, and evaluates a pitcher based on his walk rate, strikeout rate, and ground ball rate) ranked fourth in the National League, ahead of both Adam Wainwright and Chris Carpenter. That bodes well for Nolasco in 2010.

Earlier today, Tom Tango listed a few pitchers who are bound to regress in 2010. I’m here to do the opposite. Along with Nolasco, here are seven other hurlers whose 2009 xFIP gives reason for optimism this season.

Getting back to Nolasco for a moment, the reason his ERA was nearly two full runs higher than his xFIP is because he was remarkably terrible with runners on base. With no one on, opponents hit just .222/.254/.351 off of him, but they teed off for a .317/.371/.562 line with a runner on base. As a result, Nolasco had a LOB% of 61.0 percent, the lowest of any NL starter by a huge distance. Mike Pelfrey had the second-lowest LOB% of any qualified starter at 66.7 percent, with league average being close to 70 percent.

Performance with men on base does not generally carry over from year to year, which is one of the reasons xFIP is a better predictor of future performance than ERA. For instance, in 2008, Nolasco was actually better with men on base than with the bases empty, and he was dominant with runners in scoring position, stranding 75.7 percent of runners. We should expect him to perform much more evenly between those two situations in 2010, and his ERA should go way down, even if he doesn’t really improve as a pitcher.

Below is a table of pitchers with who posted an ERA at least half a run higher than their xFIP in 2009 — you should expect this group to post substantially better results this year.

PLAYER               2009 xFIP           2009 ERA
Ricky Nolasco             3.28               5.06
Carl Pavano               3.96               5.10
Livan Hernandez           4.78               5.44
Cole Hamels               3.69               4.32
Jorge de la Rosa          3.76               4.38
Jason Hammel              3.81               4.33
Mike Pelfrey              4.52               5.03
Josh Beckett              3.35               3.86

By conventional wisdom, Rick Porcello is the type of pitcher who is supposed to succeed in the major leagues. He has the perfect pitcher’s physique at 6-foot-5, 200 pounds. He can touch 95 miles per hour and throws two wipeout breaking pitches. It takes a special arm to handle the jump from A-ball to The Show, and Porcello proved he has it last year.

At FanGraphs, we track the runs above average of every type of pitch in a pitcher’s arsenal. These, called “pitch type linear weights,” examine how each pitch thrown alters the expected number of runs scored in the inning. Last season, only 23 starting pitchers — including seven of the 10 who received Cy Young votes — had fastballs that were at least 10 runs above average over the course of the season. Porcello was one of them, ranking between Cliff Lee and CC Sabathia at 14.4 runs above average. This is a case in which the statistics match the scouting reports: Porcello has one of the game’s best fastballs.

The wonder, however, is why these scouting elements that put Porcello in such high standing don’t translate to the strikeout column. Of all starting pitchers to qualify for the ERA title last season, Porcello ranked eighth from the bottom in strikeouts per nine innings (K/9) at just 4.69. Of the 23 pitchers on the best fastballs list, the average strikeout rate was 7.61, and only Joel Pineiro had a K/9 ratio lower than Porcello’s. The Tigers right-hander succeeded the same way as Pineiro, with ground balls, at the fifth-highest rate in the majors (Pineiro was No. 1).

Still, to have success going forward, Porcello will need to pitch more like he did in the Tigers’ final game last season, when he left the American League Central tiebreaker with the lead after striking out a career-high eight batters. Sustaining this type of performance for Year 2 isn’t unheard of, and given Porcello’s pedigree, pointing to Bret Saberhagen as an example is fair. Like Porcello, Saberhagen debuted in the majors at age 20, had an ERA 16 percent above league average, had good control and had a below-average strikeout rate. In his second year, Saberhagen went out and won the Cy Young, striking out hitters at a 30 percent higher clip in the process.

The Tigers don’t need Porcello to win the Cy Young this season to win their division. But to reach the peak Porcello’s stuff suggests, pitching coach Rick Knapp must scrap any instruction centering around pitching to contact. More strikeouts are the fastest way to lower your ERA, and Porcello has the stuff to do it. The sooner the Tigers convince their young star of this, the sooner he joins Justin Verlander atop the rotation.

By at least one comprehensive measure of value, Ben Zobrist was the best player in baseball last year. Yes, by Wins Above Replacement (WAR), the FanGraphs statistic that includes component statistics from both the offensive and defensive side of the ball, Zobrist was worth 8.6 WAR last year as he rode solid defense at second base just barely past Albert Pujols.

It was, to say the least, a surprise. The year before, Zobrist had accumulated a mere 1.3 WAR in his 227 plate appearances. In fact, since FanGraphs started tracking the stat in 2002, Zobrist’s 2009 effort created the biggest gap between a player’s best season by WAR and his second-best season. Let’s check out the rest of the biggest “flukes.”

                   Best WAR   Second-Best WAR    Difference
Ben Zobrist         8.6          1.3             7.3
Adrian Beltre       9.9          4.6             5.3
Richard Hidalgo     6.1          1.8             4.3
Ryan Ludwick        5.7          1.9             3.8
Magglio Ordonez     8.8          5.2             3.6
J.D. Drew           8.3          4.8             3.5
Bret Boone          7.3          3.8             3.5
Jim Thome           7.3          4.8             2.5

Luckily for the Rays, Zobrist’s big season did not come in a contract year like it did for second place on this list, Adrian Beltre. If Zobrist falls back to a Beltre-like level of performance in the future, his 2009 will be seen as a fluke, no two ways about it. On the other hand, this list also shows that not all flukes are created equal. Yes, Beltre has a big gap between his best and second-best years, but his second-best WAR total was pretty good, too.

Richard Hidalgo and Bret Boone provide a cautionary tale for Zobrist as neither came close to repeating their top WAR seasons. In their defense, Hidalgo and Boone both had good pre-2002 years that could not factor into this analysis, so it’s possible the gap between their two best seasons is not quite this large. Ryan Ludwick may yet close his gap, but like Magglio Ordonez and J.D. Drew before him, he doesn’t have Zobrist’s solid infield defense (or positional versatility) to his credit.

Since 2002, the lowest second-best WAR for a player that accumulated 8+ WAR in one season was Beltre’s 4.6. If that’s the best Zobrist does in the future, he’ll still provide the Rays great value in the short-term. Only three second basemen in baseball bettered that number last year. But we should keep in mind the careers of Boone and Hidalgo before we assume Zobrist has established a new level of performance.

With a new eight-year, $184 million contract that includes a full no-trade clause, the Minnesota Twins have essentially guaranteed their fan base that hometown hero Joe Mauer will be spending the majority of his career in the Twin Cities. The guaranteed money is steep — the contract is the fourth-largest in the history of the game — but only pays Mauer as if he’s worth an average of six wins per year over a replacement-level player. He was worth eight wins over a replacement-level catcher a year ago, so even if the power surge of 2009 doesn’t carry over, the Twins still have a good chance of getting their money’s worth.

The risk surrounding this deal is not about 2010 or 2011, but whether Mauer can continue to play well through age 35, when this new contract will expire. Catchers age in dog years, as the physical strain of crouching behind the plate 130-plus times per year takes its toll. However, a look through the history books shows that catchers who can really hit have not just survived, but thrived even after a decade in baseball.

Here are the 10 best-hitting catchers in baseball history through their age-26 season. While John Romano offers a cautionary tale of a guy who didn’t last much past 30, the
list is surprisingly positive for Twins fans. Romano is the exception, not the rule. Mike Piazza, Johnny Bench, Joe Torre and Yogi Berra were all excellent well beyond their age-27 peak, and there is certainly no discernable trend of these catchers flaming out in their early 30s.

While an eight-year deal is a risk for any player, history does not suggest that we should expect Mauer’s bat to wilt in the next few years. He may eventually have to change positions, but regardless of where he plays, we shoul

It has been a rough spring for a lot of pitchers, and while you can usually ignore spring training results, three guys in particular are pitching in a way that should worry you: Rich Harden (8 1/3 IP, 7 BB, 9 K, 2 HR), Madison Bumgarner (7 IP, 7 BB, 0 K, 1 HR) and Andrew Miller (7 2/3 IP, 8 BB, 2 K, 1 HR). But the most telling number can’t even be found in their stat lines.

Harden is coming off another injury-riddled season, so spring training represents an especially important tune-up, while Bumgarner and Miller are young guys looking to get spots in the big league rotation. Each of these guys have some real incentives to bring their best stuff even in games that don’t count. Walking seven guys while striking out none in seven innings as Bumganer has is very troubling, even if it is just seven innings. But even more telling is fastball velocity.

Over seven innings a pitcher throws about 60 fastballs, and a given pitcher’s fastball speed does not vary by much, so 60 fastballs gives a pretty good picture of a pitcher’s true talent. And fastball speed is tremendously important. The average fastball that is swung at is missed 14 percent of the time, and on average each additional 1.25 mph increases this rate by 1 percent. More swinging strikes mean less contact and more strikeouts. Not surprisingly, there is a clear trend showing that pitchers who throw faster perform better.

This is especially troubling for Harden and Bumgarner, whose fastballs have been noticeably slower during spring training. Last Monday the two pitchers actually faced off in the Ranger’s spring training park in Surprise, AZ, one of the few springing training parks with the Pitchf/x system.

Harden’s fastball was sitting in the 88 to 91 mph range topping out at 92.1 mph. His average speed last year was over 92 mph. Bumgarner worked in the 88 to 90 mph range, topping out at just 91 mph. He was regularity above 90 mph last year in the minors, and his fastball is his best pitch. However, his velocity did start to fade towards the end of last season, which makes his lack of velo this spring even more concerning. Some pitchers can succeed with a slower fastball, but the reduced speed coupled with the very poor performance is not encouraging.

Miller is a cautionary tale for Bumgarner about what can happen when a pitcher’s velocity goes away. Once an elite prospect who could regularly throw 95, his average fastball just 90.9 MPH a year ago, and his stock has tumbled significantly. A disastrous spring certainly won’t help get him back in the Marlins plans.

It’s always possible these guys are still a step behind after a long winter, and that their velocity will return. But when trying to figure out which spring training stat is most telling for pitchers, start with fastball velocity.