Looking at A.J. Burnett’s whiff rates by pitch

During yesterday’s podcast, Joe and I talked very briefly about A.J. Burnett and the swing-at and swing-and-miss rates of his various pitches over the last few years, but I think it’s something worth looking at a little more. After all, his ability to rebound from a subpar 2010 campaign is unquestionably one of the biggest stories of the upcoming season.

Burnett is primarily a two-pitch pitcher, throwing mostly fastballs and curveballs, though he’ll occasionally break out a change from time to time. You’ve got to have pretty good stuff to survive ten-plus seasons in the big leagues with two pitches, which A.J. certainly does. Whether or not that stuff is declining due to age or his Low Pitching IQ™ is another matter all together. I looked at the last three years worth of data, so it’s his last season in Toronto and first two seasons in New York. Let’s start with the ol’ number one…

Fastball

Burnett actually throws kinds of fastballs, but the PitchFX system has trouble distinguishing between his two- and four-seamers. I’ve lumped them all together in one uber-fastball category, which isn’t completely accurate but works well enough for our purposes. He’s consistently thrown the heat two out of every three pitches over the last three years, though he was a bit over that last year, seven out of every ten pitches.

Hitters have swung at Burnett’s fastball(s) about 45% of the team over the last three seasons, pretty consistently as well. A percentage point one way or the other is nothing. His whiff rates have varied wildly though, falling close to three-and-a-half percentage points from 2008 to 2009 before climbed back up a percent-and-a-half last year. It’s worth noting that A.J.’s velocity is gradually declining, which isn’t terribly surprising as he enters his mid-30’s. Still though, he averaged 93.1 mph with the heat last year (down from 94.2 in 2009 and 94.4 in 2008), plenty enough to survive in the big leagues.

Curveball

The hook has been Burnett’s bread-and-butter over the last few years, a pitch that has checked in at 38.9 runs above average since 2007. Only three pitchers own a better yakker during that time: Adam Wainwright, Wandy Rodriguez, and Roy Halladay. Hitters still swung and missed at the pitch with great frequency in 2010, though the whiff rate was down almost three percent from the year before. Overall, Burnett threw the pitch less often, but hitters swung at it more often and made more contact.

It shouldn’t be a surprise that A.J. uses the pitch primarily when ahead in the count, especially with two strikes. If a batter was down 0-2 or 1-2, there was a ~60% chance that they were getting the hook. The lack of whiffs (relatively speaking, of course) helps explain why Burnett had trouble putting batters away at times in 2010, something that really shouldn’t happen with stuff that good.

Changeup

It’s not often that Burnett breaks out his changeup, but we’ve definitely seem him do it on occasional. He’s thrown basically two or three or four changeups per start over the last three years, so the whiff data isn’t terribly reliable. It’s just a really small sample size. If he throws three per start, gets the batters to swing at it about 39% of the time, and the batters miss about 7% of the time, that means he’s getting one swing-and-miss on a changeup for every like, ten starts. The pitch just isn’t a core piece of his repertoire, and he’s tried to incorporate it more over the last few years, but at this point it’s safe to say it’ll never be a go-to pitch for A.J.

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So What Does It Mean?

Damned if I know. I just thought it was interesting that Burnett’s whiff rates for the fastball have fluctuated so much in the last three years, and it’s also noteworthy that his curveball induced about three percent fewer swings-and-misses last year. Really, I surprise the surprising thing is that his whiff rates didn’t completely tank. I was expecting them to be cut in half or something on the heater and curve, but nope.

Obviously Burnett’s strikeout rate fell off a cliff last year, and at least we know the curveball was a prime suspect. A.J. still gets a healthy does of swings-and-misses, though I suppose his location could have been so bad that when hitters did make contact, they were simply crushing the ball. I’m going to go out on a limb and say … that’s something he and Larry Rothschild should work on.