The Curious Case of Jason Castro

As we look for candidates to regress in 2014, a popular choice is Houston catcher Jason Castro for it seems the Astros backstop has two targets on his back: a high strikeout rate last year of 26.5% and a high BABIP of .351. Steamer and Oliver both project a steep drop in BABIP that will drag his batting average from a solid .276 to the .250s. As Brett Talley wrote, Castro screams regression.

Or does he?

Talley points to Castro’s strikeout rate that has been topped only 61 times in the past decade, and only four times the player matched or bettered a batting average of .276. But that measure may miss the mark. No one is suggesting Castro’s strikeout rate will worsen. When it comes to batting average, the critical question, then, is whether he can come close to maintaining a high BABIP.

On that question the evidence is more promising. In the last decade, only 38 of 1,509 batters have had an infield-fly rate lower than Castro’s 1.8%. Only 47 had a line-drive rate higher than Castro’s 25.2%. Taken together, those two select groups actually have 10 matches — players who managed both a lower infield-fly rate and higher line-drive rate. Here they are along with their BABIP, batting average and strikeout rate:

Player, year, BABIP, Avg., K-rate

Joe Mauer, 2013, .383, .324, 17.5%

Joey Votto, 2011, .349, .309, 12.9%

Howie Kendrick, 2011, .349, .297, 17.3%

Matt Carpenter, 2013, .359, .318, 13.7%

Michael Young, 2007, .366, .315, 15.5%

Joey Votto, 2013, .360, .305, 19%

Adam Kennedy, 2006, .313, .273, 14.3%

Bobby Abreu, 2006, .366, .297, 20.1%

Michael Young, 2011, .367, .338, 11.3%

Chris Johnson, 2012, .354, .281, 25%


What might we gather from this evidence?

(1) All but one of the players topped .276.

(2) The skills involved seem somewhat repeatable: Votto and Young each appear twice and as a group they generally in their careers combined a high LD rate, low IFFB rate and a high BABIP.

(3) We wouldn’t expect a player who whiffs a quarter of the time to have a batting average as high as someone who strikes out half as much while putting up similar LD and IFFB rates. Castro is unlikely to approach the median average of this group of .307.

(4) Castro doesn’t need to approach the median average to avoid significant regression. He is more likely to hit closer to last year’s mark than he is to hit in the .250s.

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Good stuff. Using xBABIP, Castro’s batted ball profile actually puts his 2013 BABIP about 8 points lower than expected (.359). His 2012 LD rate was even better, bumping his xBABIP to a cool .369 (a figure he fell well short of, though). It is, of course, a pretty small sample size for Castro. Things were very different for him his rookie year, and he has less than 700 ABs over the past two seasons. I think we can be pretty certain that he’ll continue to hit line drives (he’s a Stanford man, after all). I’m a little more skeptical about… Read more »


Thanks for the adding value to the post. I had not calculated the xBABIP — was crazy busy when I dashed off the article — and appreciate you doing so.

You raise a good point about the repeatability of very low IFFB rates and Castro’s relatively small sample size compared to the players who matched his IFFB rate and LD rate. I suspect there is a moderately strong correlation between two rates as both involve squaring up to the ball and swing plane, and perhaps someone has already done that work.


Thanks for posting this. Great analysis. Have you look at the relationship between minor league strikeout rates and major league strikeout rates? Given Castro’s minor league strikeout rates, I would have expected a lower strikeout rate from Castro given his AA and AAA rates. And maybe that is correct and he just hasn’t arrived at his true strikeout rate level. Castro’s AA(2009) and AAA(2010) strikeout rates were under 14%. His major league strikeout rates for the last two years have been over 20%. Is it possible to deduce an expected long term (mean) major league strikeout rate from minor league… Read more »