Red Sox pitcher Jon Lester has been a pleasant surprise this season. After a rough 2012, Lester managed to rebound in 2013. While his ERA dropped back to acceptable levels, his strikeout rate didn't not return to previous heights. That hasn't been an issue thus far. Lester is striking out a career-high 29.9 percent of batters this season. A big reason for that success has to do with the resurgence of his best pitch.
Some of Lester's 2012 decline can be traced to the decline of his cut-fastball. From 2009 to 2011, the pitch registered a 15.55 percent whiff rate according to BrooksBaseball.net. During 2012 and 2013, that rate dropped to 12 percent. This season, it's jumped back to 15.85 percent.
Part of that success may have something to do with Lester throwing the pitch slower. In 2012 and 2013, Lester threw his cutter slightly harder than he had in past seasons. The pitch averaged over 90 mph in each of those seasons. He's been able to get his average cutter velocity down to 89.04 mph, which is more in line with his performance pre-2012. With a pitch like the cutter, this makes sense. Throwing it slower makes it harder to time than a normal fastball, and could add more break.
The resurgent strikeout rate doesn't appear to be a fluke, either. Lester's swinging strike rate has jumped to 9.6 percent this year, his best showing in the category since 2010. Even if he sees some decline in his strikeout totals, he should be able to rack them up like he did back in his prime.
The Fantasy community tends to carry a pretty strong "what have you done for us now" line of thinking. With Lester, things appeared to be trending down entering the year. His prime seemed to have passed, and he was settling in as a good, but not elite, Fantasy starter. The rediscovery of his cutter seems to have changed that. Lester has turned into a legitimate Fantasy ace again. His surprising performance shouldn't make him a sell-high candidate.