Jon Lester: One Possible Path

By Andrew Lipsett
Here are two pitching lines from two different left-handed starting pitchers in two different seasons. Both lines have been prorated to 200 IP.

Player A is Jon Lester at age 22 in 2006, prorated to 200 IP. The picture that emerges here is of a guy who has been reasonably lucky, but still fairly skillful.
Player B is Scott Kazmir at age 21 in 2005, also prorated to 200 IP. There are a lot off differences between those lines – Lester has been luckier than Kazmir was in 2005, but in terms of his peripherals quite a bit worse overall. Lester, over 200 IP, would have allowed 3 more HR, struck out 41 fewer batters, and posted a worse K/9 to go along with a lower WHIP influenced severely by a very low BABIP.
But there’s one pair of numbers that practically jumps off the page: walks. Over 200 innings, based on his numbers this season, Lester would allow 110; Kazmir, over the same number of innings, would have allowed just 2 fewer in 2005. Their BB/9’s are virtually identical (4.97 for Lester, 4.84 for Kazmir). Ages? 22 years for Lester, 21 for Kazmir (the two pitchers were born just 17 days apart).
So, despite their differences, Lester and Kazmir shad one trait in their rookie seasons: a nearly identical and very high walk rate. We’ve certainly been talking a great deal about Lester’s since he made his debut, and I thought it important to take a look at another young lefty with similar issues.
So what has Kazmir done in his sophomore season? Prorated to 200 innings in 2006, Kazmir would allow 76 walks, an improvement of 32 over the course of a season. That works out to a BB/9 of 3.42, or just about 1.40 walks per 9 innings – a very dramatic improvement.
My point? Despite his ERA and his results, many have been questioning Lester’s potential based on his walk rates. We do have a tendency with prospects to overreact to early returns, and assume that at least to some degree, these things won’t change. But as Kazmir shows, younger players can improve dramatically from season to season. It’s too early to judge Jon Lester, based on his walk rate (the main point of contention with him so far this season). An improvement on the level of Kazmir’s would make Jon Lester a drastically better pitcher: not only would it lower the number of jams he has to work out of, and presumably improve his K rate in the process (by comparison, Kazmir’s K rate has risen from 8.42 to 9.72). Jon Lester has been very good so far. Kazmir’s example shows that next year,he could be much, much better.