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  1. Any chance you can show the data from Al Albuquerque’s slider?

    Comment by greg — September 14, 2011 @ 11:11 am

  2. Does Santos’ slider move downwards more than usual? If so, hitters might think the pitch is headed to a similar location to other sliders, but it ends up lower.

    Comment by Sky — September 14, 2011 @ 11:25 am

  3. Great stuff Josh!

    Comment by Michael Barr — September 14, 2011 @ 11:27 am

  4. This. How do you call it deception without looking at vertical movement? The pitch may start in the same location as other right handers’ sliders but end much lower. This reminds me of how Lidge was able to strike out so many hitters in years past – his slider had significant downward movement, at least to my untrained eye. This to me would induce many swing and misses below the zone.

    Comment by DD — September 14, 2011 @ 11:37 am

  5. DD,
    Movement matters, but actually does not have a very strong relationship with the effectiveness of breaking balls. The correlation between something like pitch type linear weights and vertical or horizontal movement is not very strong.

    Santos does have good movement on his slider. However, there are many breaking balls with more movement that are much less effective.

    Comment by Josh Weinstock — September 14, 2011 @ 11:43 am

  6. Sky,

    His slider does move downwards more than the average slider. But we should also keep in mind that the batter needs to decide to swing before most of this movement occurs, hence the emphasis on deception. If the batters could recognize slider, I doubt they would swing as often as they do against the pitch.

    Comment by Josh Weinstock — September 14, 2011 @ 11:47 am

  7. greg,

    The whiff rate (whiff/pitch) of Albuquerque’s slider is also excellent, at 25 percent.

    Comment by Josh Weinstock — September 14, 2011 @ 11:49 am

  8. Josh, the relationship (or lack thereof) between movement and effectiveness also extends to fastballs, does it not?

    Comment by Sean O'Neill — September 14, 2011 @ 11:52 am

  9. Sean,

    You are right, the relationship between movement and effectiveness of fastballs is also less than expected. I have found that with four-seams specifically, vertical displacement due to spin matters (significant relationship), but horizontal displacement does not.

    Comment by Josh Weinstock — September 14, 2011 @ 12:01 pm

  10. Really interesting. I enjoyed reading this.

    I saw in the comments that movement does not strongly correlate with effectiveness. I’d be curious to see a graph of 1 pitcher’s movement vs. whiff rate — here, see exactly what the relationship (or lack of relationship) is between the movement on Santos’ slider and the likelihood he gets a swinging strike on it.

    Comment by Aaron — September 14, 2011 @ 12:45 pm

  11. Aaron,

    If I do a quick logistic regression of whiff rate (dependent variable) to horizontal movement + vertical movement (independent variables) using the right handed sliders from the post (n=10000), I find that both types of movement are statistically significant, but that the effect sizes are really small. If I input Santos’ movement, then I get a predicted whiff rate (whiff / pitch) of about 15%, which is higher than average, but not nearly as high as what his whiff rate actually is.

    Of course this was pretty quick and dirty, but it does confirm the lack of importance of movement.

    Comment by Josh Weinstock — September 14, 2011 @ 1:10 pm

  12. Oops, I meant to say “whiffs” not “whiff rate.”

    Comment by Josh Weinstock — September 14, 2011 @ 1:19 pm

  13. Great post, and a great follow-up.
    That’s quite useful.

    Could you post the equation your (quick and dirty) regression gets you?

    Comment by marc w — September 14, 2011 @ 1:43 pm

  14. i know this is slightly off topic, but on the related topic of dominant relievers…
    is anyone else amazed by jonny venters getting a 72% GB rate? not to mention striking out 10/9 IP to go along with it.

    Comment by phoenix2042 — September 14, 2011 @ 3:17 pm

  15. If it’s high, let it fly

    Comment by Tsunamijesus — September 14, 2011 @ 4:00 pm

  16. Cool piece, but I can think of another slider-slingin’ Sergio who has an absurd whiff rate: Mr. Romo of the Giants.

    Comment by Evan — September 14, 2011 @ 5:12 pm

  17. I would be interested in a post about other converted position players that have been successful, and the amount of time the conversion took. I am still in awe in regard to the fact that a few years a go he was slugging.

    Comment by Dan — September 14, 2011 @ 5:31 pm

  18. I didn’t think Santos was that difficult to hit.

    Comment by Alex Avila — September 14, 2011 @ 5:35 pm

  19. marc,

    Without splitting up the data for batter handedness (so including lefties and righties), here are the results:

    Family: binomial
    Link function: logit

    whiff ~ pfx_z + pfx_x

    Parametric coefficients:
    Estimate Std. Error z value Pr(>|z|)
    (Intercept) -1.633871 0.039651 -41.207 < 2e-16 ***
    pfx_z -0.027619 0.008566 -3.224 0.00126 **
    pfx_x -0.045266 0.010214 -4.432 9.34e-06 ***

    Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ‘ 1

    R-sq.(adj) = 0.00235 Deviance explained = 0.297%
    UBRE score = -0.17328 Scale est. = 1 n = 10000

    If I look at sliders thrown to just right handed batters, pfx_z no longer has significance (p = .12) but pfx_x does. For left handed batters, both types of movement are very significant.

    I have also not accounted for the count in which these sliders were thrown, and MLBAM classification issues play a role here as well.

    Comment by Josh Weinstock — September 14, 2011 @ 5:57 pm

  20. You are a gentleman and a scholar, sir.

    Comment by Ryan — September 14, 2011 @ 5:58 pm

  21. Well Mr Santos and his great slider has now has 2 losses and 2 blown saves to go along with 6 earned runs in a span of 4.2 innings in 5 appearances.

    Comment by Steve — September 14, 2011 @ 11:03 pm

  22. This is pretty good, Josh, but next time please post about women’s rights or racism or something, instead. Thanks

    Comment by delv — September 19, 2011 @ 8:15 pm

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