There are a lot of things to like about Los Angeles Dodgers starting pitcher Clayton Kershaw. His fastball averages 94 miles per hour, yet he also can make hitters look foolish with a knockout breaking ball. He struck out 185 batters in just 171 innings a year ago, posting a K/9 that was the seventh-highest of any starter in baseball. He’s left-handed in a sport that covets southpaws. Oh, and he doesn’t turn 22 years old until halfway through spring training.
Even though Kershaw still struggles with his command and lacks experience, his ERA last season was even with Roy Halladay’s, and better than Johan Santana’s and Cliff Lee’s. When a pitcher is this good and this young, it is easy to dream about what the future may hold. If he’s already one of the best pitchers in the game (in this case, he is), what will happen when you give him some time to mature, learn how to pound the strike zone, mix his pitches and study hitters’ tendencies?
Unfortunately for Kershaw and Dodgers fans, history suggests that this may be as good as it will ever get for the young lefty. In fact, given the success he has had in the majors at such a young age, he may have already peaked.
Hitters are fairly predictable, as a group. They will show flashes of potential in their early 20s, add strength and hit a physical prime in their late 20s, and then decline in their 30s. The peak age of a position player has been shown to be around 27, with most offensive players following in this same general pattern. When you find a 21-year-old who is already a good hitter, there is a good chance greatness is in store when he gets older.
The same is not true of hurlers. They do not follow an arc-shaped career path; instead, the normal career trajectory for a starting pitcher heads downward.
There are various reasons for this observed phenomenon, the most obvious one being injury. It doesn’t take a baseball historian to rattle off the names: Mark Prior, Kerry Wood and Rich Harden are just this decade’s reminders of greatness at a young age cut short by surgery. Every pitcher, no matter how talented, is just one pitch away from the office of Dr. James Andrews on any given day.
Even putting aside the possibility of attrition, pitchers still defy conventional growth curves. While improvements are made in throwing strikes and pitching more intelligently, these marginal gains are more than offset by a bigger problem — a loss of velocity.
Scott Kazmir was the last version of Kershaw when he made his debut in the majors in 2004, throwing 94 mph at the age of 20 and racking up the strikeouts. He would develop into one of the better pitchers in the American League by age 22, but his fastball and slider began to slow down. Last year, his fastball averaged just 91.1 mph, and the Tampa Bay Rays dumped their once untouchable ace on the Los Angeles Angels in order to escape his long-term contract.
Before Kazmir, there was Oliver Perez in 2004, who broke through as a 22-year-old for the Pittsburgh Pirates. His 93-mph fastball allowed him to pile up the K’s and give Pittsburgh hope that it had an ace in the making. Two years later, with his fastball down to 91, the Pirates admitted that he wasn’t fixable and shipped him to the New York Mets.
Even the best young pitchers in the game, Felix Hernandez and Tim Lincecum, have lost 2 mph off their fastballs since arriving in the big leagues. Throwing hard is a young man’s game, and one that is very hard to sustain as the workload piles up. As young pitchers learn that they have to pace themselves to get through a six-month season, they find their radar readings less impressive than they used to be.
Unlike hitters, who tend to gain power as they age, pitchers lose it. In the past 30 years, 11 pitchers have rang up at least 180 strikeouts in a single season when they were 22 or younger. The list is not full of guys on their way to Cooperstown. Instead, it stands as a sobering reminder of just how great starts to a career can go very, very wrong. Other than Fernando Valenzuela, whose age has been the subject of much speculation, the most successful pitchers of the group: Sid Fernandez, who only three times managed to throw 200 innings in a season, and Dwight Gooden, who should have been so much more than he turned out to be. Beyond those guys, there are names such as Edwin Correa and Floyd Youmans, who were out of baseball before they could even rent a car.
Some pitchers can make the necessary adjustments and have long, great careers — but most don’t. More often, the next big thing on the mound becomes a sad story of what could have been. For every Lincecum or Hernandez, there’s a Rick Ankiel, a Dontrelle Willis, a Prior or a Kazmir. Whether it’s injury, pressure, or more often a fastball that decides not to show up to spring training one year, young pitchers are often the biggest disappointments.
Kershaw is a remarkably talented pitcher, having already accomplished quite a bit in his first two years in the major leagues. His arm is golden, his upside seemingly unlimited. But the reality of history shows that he’s more likely to get worse than to get better, and fans counting on Kershaw to win a Cy Young or two are likely to be disappointed.
Put your faith in young hitters like Justin Upton or Matt Wieters, who are on a career path that should lead them to better things in the future. Pitchers like Kershaw will break your heart.
Dave is the Managing Editor of FanGraphs.