Trade rumors are swirling around Boston Red Sox pitcher Jon Lester. This seems like an excellent time to examine how he developed as a prospect and where his career currently stands.
Jon Lester was drafted by the Red Sox in the second round of the 2002 draft, out of high school in Puyallup, Washington. He was considered a first-round talent, but a scholarship to Arizona State put his demands in question and scared teams off. The Red Sox didn't have a first-round pick that year, so they found the money to sign Lester, although he signed late and pitched in just one rookie ball game. He was considered a classic projectable lefty, throwing anywhere from 86 to 93 in high school but with a good chance to make that velocity more consistent with maturity. HIs breaking stuff was also promising but erratic. I gave him a Grade C+ in the 2003 book, noting that he could turn into Mark Mulder but could also turn into Dan Serafini.
Lester spent 2003 in the Sally League, going 6-9, 3.65 with a 71/44 K/BB in 106 innings. His component ratios were mediocre. He boosted his velocity consistency a tad to 88-92, and showed a better changeup, however his curveball and slider were still considered very erratic. I gave him a Grade C+ again, noting his long-term promise but pointing out the mediocre (at that time) component ratios. He was a high-ceiling talent but there were a lot of unanswered questions.
2004 was a mixed season. On the good side, he boosted his velocity again, to 89-93, high 95. His curve improved. He went 7-6, 4.28 with a 97/37 K/BB in 90 innings for Sarasota in the Florida State League, showing better components. He also missed three weeks of pitching with a sore shoulder. I moved him up to Grade B in the 2005 book, worried about the shoulder but liking the better velocity and stronger K/IP ratio. I wrote that he could be a number one starter, potentially, if his command sharpened a bit more and if he stayed healthy.
Lester stayed healthy in 2005, going 11-6, 2.61 with a 163/57 K/BB in 148 innings in Double-A, making a very successful transition to the high minors. His secondary pitches continued to improve, his velocity continued to bump up gradually, and he was dominant at times in the Eastern League. I gave him a Grade B+ and wrote that "there is every reason to think that Lester will be a successful major league pitcher."
Lester split 2006 between Triple-A and the majors, pitching brilliantly at times but with league-average results overall, which was still very credible for a 22 year old rookie in the American League East. Then he had the bout with cancer, non-Hodgkin lymphoma, but came back in 2007 and again posted league-average results in 63 innings.
The big breakthrough came in 2008: 16-6, 3.21 ERA, 144 ERA+, 152/66 K/BB in 210 innings, 5.0 WAR. He threw a no-hitter against the Kansas City Royals on May 19th. As you know, he's been one of the top starters in baseball ever since. His only bad year was 2012, and even that year he ran up 3.1 WAR.
Through 1519 innings, Lester has a 3.64 ERA, 3.60 FIP, 120 ERA+ with a 1386/529 K/BB ratio and a 110-63 record in 241 starts. He has a 33.8 career fWAR.
Through age 30, Lester's list of comparable pitchers via Sim Score: Kevin Millwood, Andy Pettitte, Josh Beckett, Mark Mulder, John Lackey, Jack McDowell, Pat Hentgen, Bartolo Colon, Jake Peavy, and Roy Halladay. PECOTA from Baseball Prospectus brings up a different set of names: Jose Rijo, Warren Spahn, Gavin Floyd, Erik Bedard, Kevin Appier, Dean Chance, Lackey, Adam Wainwright, and Juan Guzman.
The presence of several close contemporaries is interesting but complicates the historical parallels. In terms of projection, Spahn is the only present Hall of Famer on the list. Pettitte and Halladay will be borderline candidates; it is too soon to know about Wainwright. Everybody else was a solid starter at least and at times outstanding, though short of Hall standards, often for durability reasons.
Lester's been durable and healthy but as he gets into his 30s his abilities might fade quickly. Of course, there's no sign of that right now; indeed, he's on course to have the best season of his career.
As a prospect, Lester was a textbook case of a projectable young pitcher who gained strength, boosted his velocity, polished his secondary pitches and sharpened his command in a steady, nearly linear way. It seldom happens this smoothly and Lester did it despite his bout with cancer.