Sometimes I try to explain a pitcher's bad performance in a common metric like ERA by something out of his control-- bad defense, bad luck, or just random chance. Sometimes there are bad pitchers with runs of success that convince people they're good, and I try to explain that they were never good in the first place. Then there's the case of what Randy Wolf is experiencing this year: he's a good pitcher having a terrible year. No bad luck or chance or bad defense can really explain what's happened, he's just been unpredictably bad.
In his career, Wolf has put up a ratio of 7.3 strikeouts per nine innings to 3.3 walks per nine innings, and induced 38% ground balls. Those are the numbers of a good pitcher. Last year, in Wolf's best season, the K/BB per nine ratio was 6.7 to 2.4. This year it's 5.8 to 4. That's a major dropoff.
But let's step back, because I'm actually writing this post as a defense of Randy Wolf with an eye for optimism in the next two years of his deal. Good pitchers can have bad years, it's happened before and it will happen again. There's really nothing that jumps out at me in terms of Wolf getting lucky or unlucky this season. There's no significant change in any of the stats that tend to vary (mainly BABIP and the rate of home runs per fly ball).
The question I do want to look into is if there has been a dramatic change in Wolf's stuff or pitch selection. The first thing I notice in looking through the pitch f/x data is that his fastball velocity is slightly down this year, from about 89 to closer to 88 this season. This could be the result of another change-- more moving fastballs. The pitch f/x algorithm has split nearly half of Wolf's fastballs, with about the same velocity as the usual fastball, into the category of "2-seam fastballs", which tend to be slightly slower and have less movement.
So is Wolf just throwing slightly less hard, messing with pitch identification, or making an effort to put more movement on his fastball this year? I tend to think it's the former, because another pitch identification system (in which stringers manually select what type of pitch was thrown) at Fangraphs has Wolf's rate of fastballs thrown at about the same as his career rate.
Nothing really seems to be wrong with any of his pitches except a slight velocity reduction across the board of about 1 mile per hour. It's impossible to if that's an exact number do the the inexact nature of pitch f/x cameras and differences in parks, but it seems plausible to conclude that Wolf has lost just a little bit of stuff this year.
In terms of effectiveness, his fastball has been worth a career-worst -1 runs per 100 pitches, compared to a career average of .64 runs per 100 pitches. The curveball has been similarly ineffective. On the other side, the changeup and slider have been much more effective than the career rate. The only conclusion that I am comfortable drawing out of that is that something is probably wrong with the fastball this year. If the velocity's down and it's getting hit harder, it's an area of concern.
Wolf's swinging strike rate is also at a career low, at 6.3% after being in the 8s and then dropping to 7.4 last season.
I began looking into Wolf expecting to find a way to look for optimism, but to be honest I didn't really find much. Wolf has been a good pitcher in his career but it's looking like this year is part of the decline towards the last part of his career. However, I'm actually pretty confident that Wolf will bounce back next year and put up better numbers in categories that matter like K%, BB%, and Swinging Strike %. Good pitchers are good pitchers, and the loss of 1 mile per hour in velocity does not make them go from a 4.2 FIP talent to a 5.5 FIP talent in 1 year.
It's probably time to adjust our expectations for Wolf slightly from the 4.2 FIP and 200 innings we were hoping for at the start of this year. I still think the signing has a good chance of working out, and if the Brewers didn't have Wolf right now, they'd be looking to sign someone like him to a 2 year, $20 million deal this offseason anyways. It has not been a positive year for the big free agent signing of 2009-2010, but due to the fact that he hasn't altered his ways too much from the successful days of the past, I'm confident that we will be seeing a more productive season out of Randy Wolf come 2011.