Luis Mendoza has a 3.58 ERA in August, which has followed a solid July performance, which in turn followed a commendable June performance. As tough as it is to admit, it's time for the stats crowd, myself include, to swallow our pride and climb aboard the Luis Mendoza bandwagon.
We were skeptical of Mendoza after his MLB promotion seemed to be based upon a 2011 AAA performance which, from a statistical perspective, was a foundation of smoke and mirrors. The telltale signs of flukey success were all there--the .268 BABIP, the 0.31 HR/9, the 13.6% strikeout rate (MLB average is 18.5%, which Mendoza was far below despite facing much easier competition), the 9% walk rate (again, worse than the MLB average of 8.5% despite facing easier competition). Mendoza looked like a bad pitcher that had found the good graces of the baseball gods for one year.
And then when the Royals front office ignored all of the statistical warning signs and bought into Mendoza's "great" 2011 performance hook, line and sinker, we statistically inclined fans smiled snarkily on the sidelines as Mendoza fulfilled our expectations to a tee for the first two months of the season. In April and May, Mendoza had more walks than strikeouts. He allowed 28 runs in 39 innings. And it could have been even uglier as he was lucky to have only allowed 2 home runs during that stretch.
And then something happened. I've heard that in June, Mendoza began throwing a cutter which turned around his season. I don't know the root cause, but the results speak for themselves. Check out the evolution of his strikeout and walk rates:
Mendoza has faced over 330 batters since this trend of improvement began in June, and strikeout and walk rates tend to stabilize relatively quickly, so this sample size is significant. Again, the league average strikeout and walk rates are about 18.5% and 8.5% respectively, and for starters, the rates are a little lower.
Sometime around early June, something clicked for Mendoza, and he went from being unable to get strike three and all too able to throw ball four to suddenly being an approximately league average pitcher in terms of strikeout and walk rates. Mendoza lags league average in K% just slightly, but he compensates with his above-average ability to induce groundballs.
While I continue to suspect that Mendoza's 2.18 ERA in AAA last year was a statistical fluke, the statistical evidence suggests just as strongly that Mendoza's sub-4.00 ERA over the last 3 months is the real deal. At this point, Luis Mendoza looks for all the world like an MLB average starting pitcher.