So Cleveland's charts read 4-5 inches low, Boston's read 3-4 inches low, and New York's exaggerate horizontal movement. The only other places he has pitched are LAAA and BAL. Fortunately they both look calibrated and accurate.
In LA his cutter was (2.24 / 5.03)
In BAL his cutter was (2.01 / 6.45)
That is a cutter, a pure cutter, not a slider at all.
I agree that the vertical movement error (which seemed to show up in Fenway's readings only during this past homestand, and not all season long) makes it impossible to derive accurate spin RPM data for Beckett's cutter during the last two games. When I wrote that Beckett's cutter is becoming more of a slider, I was referring to
increased horizontal movement on the pitch in 2011 compared to 2010 and 2009 (prior to 2009 he threw so few of them that it is harder to generalize). Those quantitative changes aren't enormous, but to my eyes they confirm observation that Beckett's cutter looks different and seems to move more.
When the cutter's horizontal movement data are broken down by batter handedness, the picture becomes clearer: Beckett's cutter is definitely a cutter when thrown to lefties (
1.7" movement, N = 85)), but the same pitch
registers 2.2" (N = 90) when thrown to righties. It confirms observation (again, this is my impression, not a claim of proof) that Beckett tries to get more movement on the cutter when throwing to the same-handed batter: it moves more because Beckett throws it a little bit differently, with more torque from the wrist and slightly lower velocity (~.3 mph lower, to be precise). Hence, more of a slider than before, even if it is still accurate to classify the pitch as a cutter. By way of comparison, most major-league cutters have little if any horizontal movement, but Beckett's cutter is starting to behave a little more like Mariano Rivera's cutter. I wouldn't claim that it gets the same results, but it has been an increasingly effective weapon the last two years.
This assumes that the pitch classification is correct. I think that's fair, since pitchfx has learned to read Beckett quite well, as phragle's charts show. It also assumes that the horizontal movement data are reliable, but does not depend on vertical movement readings. The change is marginal, and if it generated the hypothesis rather than confirming observation, it might be ignored, but I think we're seeing a change that is both real and intentional.
So, to be clear, what I wondered about is why you said part of the BABIP drop was due to variety of pitches instead of just luck. Were it the case that lower BABIP correlated to a pitcher's variety of pitches/speeds, that seems like something that would have popped in the prior BABIP studies, don't you think? Seems shaky to argue that Beckett's current mix of pitches and speeds is the most diverse (or anywhere near the most diverse) of any pitcher who has been included in the numerous studies, right? And if it's not, then why would (in his case this year) the BABIP be skill rather than luck?
Seems like you're really just tossing out a lot of research on BABIP without any basis that I can see. Pitch FX is wonderful, but I continue to be of the view it does not explain all problems all the time and we get in trouble when we try to make it do so.
I am not tossing out any research that I can think of, nor am I using pitchfx to explain all problems. Instead, I am using pitchfx data, with appropriate reservations as stated, where they can help confirm or reject hypotheses arrived at by watching Beckett pitch. If hitfx data were publicly available, I think it would be possible to put BABIP studies on a firmer footing by quantifying the quality of contact -- speed of groundballs, velocity and trajectory of flyballs and line drives. I don't have those data and am not attempting that exercise in this thread.
Luck is not only or always about BABIP -- it is as likely to be about power suppression, as effectivelywild argues below.
Well, I don't know if "keeping hitters off-balance" will result in a noticeably different BABIP (after all, for all of the times that they aren't expecting your next pitch, there will be times when they guess right as to what's coming and will pound it) but I imagine it would also show up in K and HR rates. After all, if you're sitting dead red and you get a change up or a slider, you're more likely to miss the pitch---same thing if you're thinking "ok, this is definitely going to be a change up" and you get a cutter---your timing is going to be off and you're more likely to miss the pitch. Similarly, I imagine "keeping hitters off-balance" would lower your HR rate, as its hard to hit the ball hard if you have no idea what pitch is coming next.
Beckett's K rate is the same in 2011 as in 2010 (~8.2), but the HR/FB rate has gone from 14.2% to 4.5%. The 86% LOB% is fortunate as well. xFIP 3.30 vs. ERA 1.69 suggests that Beckett has been very good, but his results have been better than that. There's still no way to explain why he grooved so many fastballs in 2010, and hasn't done the same this year. We could examine some game-to-game strike zone charts, but that's likely to give us more anecdotes than explanations. Fastball command is still a black box.