Mike Podhorzer, who is an expected-stat wizard at FanGraphs, recently updated his most successful statistic: expected strikeout percentage (xK%). This metric uses the most important aspects of a pitcher’s game: strike rate, swinging-strike rate, looking-strike rate, and foul-strike rate to determine how often they should be striking hitters out. In his research, Podhorzer found that 93 percent of a pitcher’s strikeout rate can be attributed to such aspects.

Given that this xK% is so predictive, maybe we can use it to identify current Cubs pitchers who either under or overperformed last season.

Jon Lester – K%: 24.8 vs. xK%: 23.3 (+1.5)

Jake Arrieta – K%: 23.8 vs. xK%: 23.9 (-0.1)

Kyle Hendricks – K%: 22.8 vs. xK%: 24.2 (-1.4)

John Lackey – K%: 24.1 vs. xK%: 23.7 (+0.4)

While the difference between K% and xK% was negligible for Arreita and Lackey, Lester and Hendricks each had about a 1.5 percent difference. In Lester’s case, we can see that he may have recorded more strikeouts than others with similar peripherals. For Hendricks, it’s not inconceivable to think that actually having a 24.2 percent strikeout rate would’ve secured him the Cy Young.