Luis Mendoza, who is probably not your definition of a slumpbutser, takes the mound for the Royals this afternoon. Mendoza's 6.00 ERA after five starts this season isn't nearly as beautiful as the right-hander's hair, but his peripherals suggest that Mendoza is the same pitcher as last season.
Mendoza is striking out a few more hitters, but also waking a few more, making his K/BB ratio essentially the same as his 2012 K/BB. He' still forcing groundouts at an above average rate. Mendoza posted a 4.36 xFIP last season, and has a 4.07 xFIP this season. He's still pitching at an acceptable level for a team's fifth starter.
The 29-year-old has struggled/been the victim of bad luck with runners on base, as his LOB% is 51%; Mendoza is stranding 21% less runners this season than last season, which leads to the higher number of runs allowed. Expect Mendoza's LOB% to start increasing back towards league average, which should cause his ERA to decrease.
A.J. Griffin has a fairly spectacularly 3.22 ERA through his first 134 innings pitched in the major leagues, but there is reason to suspect that Sunday's starting pitcher for the Athletics is a back of the rotation starter.
The right-hander throws a fastball, slider, curveball and changeup. He is not a power pitcher, as the average velocity on his fastball is 89 mph. Griffin does get good movement on his offspeed pitches and changes speeds quite well, especially on his curveball. The average velocity on his curveball is 68 mph, making it his best strikeout pitch.
Griffin's strikeout and walk numbers are essentially average; he strikes out 2% less hitters than a league average pitcher, but also issues 2% less walks. Griffin, like Tommy Milone, is a flyball pitcher who has done a good job keeping his HR/FB rate in check.
The 25-year-old owns a career xFIP of 4.11, perfectly acceptable for a back of the rotation starter. Griffin has managed to post an ERA almost a full run lower than his xFIP by stranding 79.4% of runners in his career, and allowing a BABIP of .262.
Even if Griffin is pitching a bit over his head, he's still a useful arm for the A's. Given the the Royals offensive performance of late, he seems like a good candidate continue his success.