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All About A.J.

It would be an understatement to say that the Yankees need A.J. Burnett to pitch better in 2011 than he did in 2010.  He set career worsts in losses (15) and ERA (5.26, 81 ERA+); his .317 BABIP and 11.9% HR/FB likely inflated his ERA beyond his actual talent level, but it's impossible to pin Burnett's struggles solely on "bad luck."  He also experienced the lowest strikeout rate of any season since 2001, and his walk rate remained constant with his career average.  He's only two years removed from a 5.5 WAR season in which he won 18 games and led the league in strikeouts, but after last year's struggle, that feels like much longer ago.  

Apparently, Burnett was under some sort of emotional turmoil last year that the Yankees are not discussing (GM Brian Cashman said this about A.J. two weeks ago: "He knows he has a problem, and he's doing all he can to fix it.").  There's obviously not much to say about the root cause of A.J.'s struggles last year - maybe he couldn't focus, maybe he was hiding an injury; we really just don't know.  However, what we can do is look at the tangible elements of his performance that declined from previous years.  

You may often hear commentators refer to A.J. as a two-pitch pitcher due to his extreme reliance on one offspeed pitch in strikeout situations.  These days, A.J.'s repertoire consists of four distinct pitches: a four-seam fastball, a two-seam fastball, a knuckle-curveball, and the occasional hard changeup.  He used to throw a slider, but there is no PITCHf/x evidence for this after June of 2008 (he threw 40 that year).  He'll throw his pitches from a high three-quarters angle, and he'll sometimes lower his angle when throwing his curve.  

This chart shows the aggregated spin movement (over the past three years) for the five pitch types he has thrown.  Starting with the four-seamer, which he throws more than any other pitch, I will go through his arsenal and see what has changed since 2008, what's still working, and what we should look for moving forward to 2011.  If you're unfamiliar with the metrics here, you can use this post as your glossary.  




Pitch grip


FF Pitch# Pitch% Swing Rate Whiff Rate Zone Rate Chase Rate Watch Rate RV/100 xRV/100
2008 1589 .469 .469 .165 .495 .279 .337 0.73 -0.25
2009 1621 .482 .430 .122 .482 .245 .371 0.87 0.52
2010 1517 .488 .454 .134 .504 .262 .356 0.81 -0.12

4727 .479 .451 .141 .493 .262 .355 0.80 0.05


GB Rate FB Rate LD Rate PU Rate HR/FB+LD wOBAcon*
2008 .342 .327 .209 .122 .081 .412
2009 .280 .434 .208 .079 .106 .402
2010 .312 .395 .176 .116 .110 .413

.311 .386 .197 .106 .100 .409


*wOBAcon is the weighted on-base-average for pitches put in play, and the league average should be .345-.350. 

Over the past three years, A.J.'s four seamer has averaged about 5 and a half inches of tail into right-handers and a bit less than 9 inches of "rise" relative to a spinless pitch.  From my observations, this is slightly more movement than the typical four-seamer.  It'll find the plate about half the time he throws it, which isn't spectacular.  It doesn't miss a ton of bats (the league average whiff rate for four-seamers is 15%, and A.J.'s average is a bit under that over the past three years).  The groundball rate isn't good, and the high wOBA on contact indicates that batters are crushing the pitch.  All of this leads to a combined 0.80 RV/100 since 2008, which is around 24% worse than the league average pitch.  The expected run value metric, which substitutes league average run values for actual outcomes, considers it to be about average; however, over three years, the sample gets significant enough that "true" run values are worth taking seriously.  Also take note that his fastball appeared to lose some velocity last year; though the numbers on the fastball in 2010 don't look particularly different from the previous two seasons, the velocity decrease will be interesting to look at moving forward.   




Pitch grip (hat-tip to Mike Fast for this image)


FT Pitch# Pitch% Swing Rate Whiff Rate Zone Rate Chase Rate Watch Rate RV/100 xRV/100
2008 547 .161 .473 .143 .527 .274 .347 -0.62 -0.65
2009 576 .171 .455 .084 .441 .289 .335 -0.51 0.53
2010 617 .198 .465 .146 .439 .312 .339 -0.01 -0.26

1740 .176 .464 .125 .467 .293 .341 -0.37 -0.12


GB Rate FB Rate LD Rate PU Rate HR/FB+LD wOBAcon
2008 .606 .197 .174 .023 .061 .304
2009 .559 .206 .191 .044 .056 .294
2010 .643 .196 .140 .021 .063 .343

.603 .200 .168 .029 .060 .314

The two-seamer is a very interesting pitch.  It gets a ton of movement, almost 10 inches inside on a righty and 4 inches less "rise" than his four-seamer, and is thrown at just about the same velocity as is the four-seamer.  The extra movement on the pitch helps it keep a groundball rate of over 60%, twice as high as that of the four-seamer.  The batted ball profile helped limit hitters' productivity (look at the lower wOBAcon on the two-seamer).  He'll sacrifice some whiffs - fewer if you take away the 2009 season - but makes up for it with the extreme ground ball rate.  On average he also throws a few more two-seamers than four-seamers out of the zone, but makes up for that with more chases.  Both implementations of the run values consider the pitch to be better than average.  



CU Pitch# Pitch% Swing Rate Whiff Rate Zone Rate Chase Rate Watch Rate RV/100 xRV/100
2008 964 .285 .387 .466 .357 .312 .471 -1.10 -1.41
2009 1051 .312 .390 .427 .378 .308 .458 -1.79 -1.65
2010 844 .271 .398 .366 .301 .298 .398 0.35 0.07

2854 .289 .391 .422 .349 .305 .447 -0.93 -1.06


GB Rate FB Rate LD Rate PU Rate HR/FB+LD wOBAcon
2008 .656 .180 .188 .010 .031 .340
2009 .641 .226 .148 .031 .024 .314
2010 .591 .250 .174 .009 .065 .400

.628 .186 .168 .018 .042 .351


A.J.'s curveball is his signature, and it's really his only out-pitch.  It's a hard knuckle-curve and averages around 82 mph.  After being elite in the linear weights department in 2008 and 2009, it dropped to a below-average pitch in 2010.  I could find a few things that affected it:
The first thing to notice is the whiff rate.  It's still above average at 36.6%, but it's still down 6 percentage points from 2009 (which was another 4 down from 2008).  Over the course of a season, which would average to roughly 1000 curveballs thrown and 390 swings taken, that's about 25 pitches that have turned from swings-and-misses in 2009 to contact (either foul or fair) in 2010.  Not a ton, but enough to make a difference.  
His batted ball rates trended in the wrong direction everywhere (fewer grounders, more flies, more liners, and fewer pop-ups); the differences were slight, so I won't spend too much time on that, though they surely made an impact on some small level.  
The curveball was in the zone much less frequently in 2010 than in 2009, and it didn't correspond with a large enough increase in chases.
When the curveball was in the zone, it wasn't freezing hitters.  The watch rate decreased from over 47% to under 40% last year.  And those extra swings produced a lot of contact - on curves in the strikezone last year, Burnett had a whiff rate of 7.8%, down from 21.9% in 2009.  That's a huge difference, and I can't say I have a good reason for why it happened.  Burnett's vertical plate locations look pretty similar from year to year, so it doesn't appear that there was a significantly larger amount of "hanging curveballs" in 2010 than in 2009.  



Pitch grip (h/t again to Mike)


CH Pitch# Pitch% Swing Rate Whiff Rate Zone Rate Chase Rate Watch Rate RV/100 xRV/100
2008 167 .049 .383 .359 .311 .226 .269 0.62 0.46
2009 115 .034 .400 .152 .348 .293 .400 0.63 0.88
2010 108 .035 .417 .289 .250 .284 .185 -2.10 0.81

395 .040 .397 .280 .301 .264 .294 -0.13 0.67


GB Rate FB Rate LD Rate PU Rate HR/FB+LD wOBAcon
2008 .583 .250 .125 .042 .000 .319
2009 .684 .053 .263 .000 .000 .367
2010 .467 .400 .133 .000 .000 .134

.586 .224 .172 .017 .000 .284


The changeup is the pitch that A.J. throws the least.  He'll only throw 3 or 4 per game, so I won't dwell on it too much.  It's hard (upper 80s) and gets splitter-type action; results-wise, it's really not a great a pitch.  He's missing a few more bats with it (28.9% whiff rate up from 15.2% last year), but is also throwing it for a ball more (53.7% ball per pitch from 47%) and is getting fewer called strikes (4.6% called strikes per pitch down from 13%).  Like I said, there's not really a whole lot to say about this pitch since he hasn't used it very much.  Despite A.J.'s announcement last spring that he was going to use his change more, his overall pitch selection (3.4% in 2009 to 3.5% in 2010) remained unchanged.  



So what does this mean for A.J. Burnett in 2011?  There are a few things that I take away from these numbers.  Clearly, A.J.'s curveball wasn't nearly as effective in 2010 as it was in 2008 and 2009, but why?  The way I've broken down his struggles with the curve (essentially more balls, fewer whiffs and called strikes) only tells you that it happened.  Not why it happened or how it can be fixed.  I will throw out a thought, though.  Since A.J. rarely throws anything other than a fastball or a curveball, is it possible that hitters were able to "sit on" the curve and were ready for it when it was in the strikezone?  A.J.'s been in the majors for a while, and I don't understand how things would change that drastically this late in his career.  That's a question that's best presented to the opposing hitters.  If this theory has any traction, then it might be good for A.J. to refine his changeup so that he can use it as a consistent part of his repertoire (maybe somewhere around 10% of his total pitches).  As for something that I can say with some level of conviction: from these data, I would conclude that A.J. should throw his two-seamer more.  It gets a lot more groundballs than the four-seamer, misses enough bats, and finds the strikezone enough to be effective.  Why not go with the pitch that can get you weak contact and a double play ball?  I'm very curious to see what kind of an influence new Yankee pitching coach Larry Rothschild has on Burnett, and if he can turn him back into a productive major league pitcher.       

The data in this post are courtesy of Joe Lefkowitz's PITCHf/x tool.