The Detroit Tigers rotation is underrated. Yes, the group headlined by Justin Verlander, the one that helped carry the Tigers to the World Series last year, do not receive enough attention. You probably know that the Tigers have good starting pitching. You may not know that they have one of the best rotations any team has put together recently.
Heading into the second month of the 2013 season, here are the four best starters in the American League by Fielding Independent Pitching (FIP), which evaluates a pitcher based on their walks, strikeouts, and home runs allowed and is scaled to expected ERA.
1. Anibal Sanchez, 1.34
2. Yu Darvish, 1.60
3. Max Scherzer, 1.69
4. Justin Verlander, 2.11
That’s right – by FIP, the Tigers have three of the league’s top four pitchers through the first month of the season. Doug Fister, who takes the mound against the Astros on Friday, rates 14th at 3.14. Combined, those four pitchers have thrown 144 innings while posting a 2.06 FIP, which is 49 percent better than league average. To put that in some context, Pedro Martinez in 2000 — in what some consider the best single season pitching performance of all time — posted a FIP 54 percent better than league average in 217 innings. For the first month of the season, the average of the Tigers top four starters have been almost as good as Pedro Martinez at his absolute peak.
They can’t keep this up, because no one can keep this level of performance going for any sustained period of time. In particular, they’re due to give up some home runs, as they’ve only allowed four long balls between them in 22 starts. Only 3.5% of their fly balls have gone for home runs, when the league average is around 11%. Eventually, they’re going to give up some long balls.
But, even accounting for the expected rise in home run rates, these guys are on another level. By xFIP, which replaces home run rate with expected home run rate based on number of fly balls allowed, they still come out 29 percent better than average as a group, with Scherzer taking the top spot and Sanchez falling all the way to #3.
In fact, the Tigers are the poster child for why using ERA to evaluate a starting pitcher can lead to mistakes. Detroit’s rotation ranks just 6th best in the majors by ERA this year, but that’s because the defense behind them is simply not up to par. The Tigers made a conscious decision to trade defense for offense by moving Miguel Cabrera to third base to make room for Prince Fielder, and while it improved the offense, the Tigers defense simply doesn’t convert that many opportunities into outs when given the chance.
This year, the Tigers starters have allowed a .328 batting average on balls in play, third highest of any starting rotation in baseball. By Ultimate Zone Rating, the Tigers rank 26th in baseball in fielding, and it’s not like it’s just Rick Porcello — the weak link in the rotation at the moment — giving up all the hits; Sanchez (.316), Verlander (.324), and Scherzer (.380) have all given up more hits on balls in play than the league average.
If you rely on ERA to evaluate the Tigers pitchers, you’re going to end up penalizing them for the team’s decision to prioritize offense over defense among position players, and we shouldn’t hold Miguel Cabrera’s lack of range against anyone besides Miguel Cabrera. FIP focuses on solely the events where the defenders behind a pitcher are not involved, and can give us a better view of how they’ve performed on their own, without the impact of their defense clouding the picture.
So, how does this fearsome foursome stack up against other great pitching staffs of recent years? Well, the best rotation (by FIP) any team has put together in the last 20 years belongs to the 2011 Phillies, barely edging out those mid-90s Braves teams that featured Greg Maddux. As a group, the Phillies posted a 2.98 FIP, which was 23 percent better than league average. This Tigers rotation would destroy that mark at their current pace, but of course it’s easier to beat a single season record in a month’s time than to do it over a full six months of baseball.
However, their ridiculous April performance has given them a pretty good shot at besting the Phillies 2011 mark. Because their first 162 innings are already in the books, they only need to post an ERA just 19 percent better than league average over the remainder of the season in order to match the Phillies mark. Last year, Detroit’s starters FIP was 15 percent better than average, and they only had Anibal Sanchez for the final two months of the season. With Sanchez in Detroit for the entire season, the Tigers rotation this year is certainly better than last year’s, and might even be as good as that Phillies staff that led Philadelphia to 102 victories.
Cabrera and Fielder might be the two biggest guys on the team, but the starting rotation is the foundation of this Tigers team. No team has a better group of starters this year, and few teams have put together this kind of group in recent history.
Dave is the Managing Editor of FanGraphs.