First, a bit on Mitre’s season thus far. He’s pitched twelve times in 2010, including two starts in May. He’s received good results in his first 25 innings, posting a 2.89 ERA; however, his controllable rates are trending poorly: his strikeouts are about the same as last year, but his groundball rate has dropped considerably and he’s walking one more batter per 9 innings than he was in 2009. This year, the balls in play have turned from hits to outs, and the flyballs he’s given up have turned into homers less frequently than last year. It’s probably not too realistic to expect his ERA to remain under 3 for that long, but surely the Yankees would be just fine with getting a mid 4 ERA out of their sixth starter. Onto the PITCHf/x data!
Though Mitre is a sinkerballer for the vast majority (65.5% sinkers this year, 67.9% last year), he does have a five-pitch arsenal. He also works with a four-seamer, a tight curveball, a changeup, and a slider. This year, there’s been a greater rate of four-seamers and sliders; from what I could see, the slider as it is now was not utilized at all last year. To compare pitch percentages from 2009 to 2010, here are the pitch column charts.
As for Mitre’s groundball rate, which has dropped from .572 last year to .507 this year: it appears that the drop has to do with Mitre’s secondary pitches, since the rate on Mitre’s sinker has remained constant - .586 last year to .591 this year. For what it’s worth, this is significantly above the major league average of ~.52 for sinking/two-seam pitches. Between the small sample we’re working with and the fact that most pitches put in play are going to be on Mitre’s sinker, I’m not too concerned right now about the decrease in ground balls.
Another thing to mention about Mitre is his decreased velocity this year. I assumed that one more year removed from arm surgery, he would be throwing harder than he was last year, but this hasn’t been the case so far:
Pitch 2009 mph 2010 mph SI 90.97 89.38 FF 91.10 89.31 CH 83.51 81.87 CU 78.52 77.81 SL N/A 82.06
Now, it’s not uncommon for pitchers to gain velocity throughout the course of a season, so I don’t know if it’s reasonable to fret about the one and a half mph drop at this point in the season. I could go on about Mitre’s splits (whiff rates, etc.), but I’m not convinced that it would be productive given the relatively limited sample this season - after the sinker, the pitch that’s been swung at most frequently has been the changeup, which has been swung at only 23 times. That’s not really giving us a whole lot to work with.
To conclude - I’m sure many Yankee fans are not too thrilled with seeing Mitre take the ball every fifth day for the next month, given his weak performance last year. And if Mitre falters, it’s certainly not a given that he makes the rest of Pettitte’s starts, particularly since the Yankees have the talented Ivan Nova ready to go at Triple A.