Jon Lester's Cutter Is a Cut Above the Rest

After bouncing back-and-forth between the majors and the minors in 2006 and 2007, Jon Lester finally stuck in the Red Sox's rotation full-time in 2008. He quickly became one of the best pitchers in the league. From 2008 through 2011, Lester was worth well over 4 wins per season, as measured by fWAR. According to RA9-WAR, he was worth nearly 6 wins per season during those years. Great peripherals; even better results.

Lester experienced a mid-career hiccup in 2012 and 2013, though. While he finished each of his first four full seasons with an ERA below 3.50 (in the AL, while pitching in hitter-friendly Fenway Park), his ERA across the 2012 and 2013 seasons was 4.28. His peripherals were a little better, as his FIP was 3.84 and his xFIP was 3.86. Still, it wasn't the kind of performance Red Sox fans had become accustomed to seeing. His strikeouts were down. He was allowing more base runners. And those base runners were scoring more often. Lester was only worth about 3 wins per season in 2012 and 2013, according to both fWAR and RA9-WAR.