From 2008 to 2011, the Red Sox Jon Lester was among the best pitchers in baseball. In fact, he ranked behind only four pitchers, who combined to win four Cy Young Awards, over those four seasons in Wins Above Replacement (see chart below). This year? Lester’s WAR is below zero.
LesterPart of the issue has been Lester's steadily declining strikeout rate. After ranking first among all qualified starting pitchers in 2010, he was 18th in 2011 and has dropped to 54th this season. He’s actually closer to the bottom than the top among qualifiers.
The effectiveness of Lester’s curveball also has diminished noticeably over the last three seasons. Opponents are hitting .327 against his hook this season, compared to .200 last season and .136 in 2010. The .904 OPS opponents have registered against Lester’s curveball is the third-worst among starting pitchers who have thrown at least 200 curveballs this season.
Lester has been able to maintain his effectiveness against left-handed hitters -- his numbers this season are not all that different from 2009.
Most Wins Above Replacement
Starting Pitchers from 2008-11
However, it’s against right-handers that Lester is regressing, and in a big way. In 2010, right-handed batters hit .219 against Lester. That average increased to .244 last season and in 2012, righties are hitting .286 with an .805 OPS.
It appears that Lester has lost the ability to pitch hard and inside to right-handed hitters. When looking at his fastball and cutters against right-handers, he’s generating fewer swing-and-misses with such pitches. Lester’s swing-and-miss rate has dropped from 22.0 last season to 16.4 in 2012.
Fewer swings and misses mean right-handed hitters are teeing off on Lester’s fastball. They’re hitting .351 against his fastball and cutter, up from .241 last season.