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Talking Sabermetrics: Astros Hitter x-BABIP

The forward view for most Astros' hitter is positive, using x-BABIP.

Bob Levey

A couple of weeks ago I wrote about Astros' pitcher x-BABIP. The x-BABIP calculation for pitchers is a newer concept than x-BABIP formulas for hitters. And we probably are somewhat more confident in the x-BABIP benchmarks for hitters, given its wider use. Today, I will complete the x-BABIP discussion by comparing Astros' hitters x-BABIP to actual BABIP.

Take a step back for the context of this discussion. As you probably know, BABIP is "batting average on balls in play" and x-BABIP is "expected BABIP." The common usage for the x-BABIP comparison is to assess whether the batter's hit results (such as batting average) are lucky or unlucky. A hitter who posted an actual BABIP less than expected BABIP may have been unlucky or vice versa. This, in turn, might tell us whether the batter's performance is likely to revert upward or downward in the next season. There are no guarantees, of course. But it's an interesting exercise.


In October, 2011, I compared Astros' hitters 2011 BABIP to their x-BABIP for that season. We can review the 2011 comparison and see how successful it was in predicting positive or negative BABIP regression for 2012. In my view, these kinds of comparisons are more valuable in suggesting the direction of the future BABIP, as opposed to predicting the actual BABIP for the next season. Therefore, I will compare the 2012 actual BABIP to the 2011 BABIP, inquiring whether the BABIP increased or decreased as suggested by the 2011 x-BABIP.

Bogusevic, Paredes, and Downs posted BABIP higher than x-BABIP, suggesting that BABIP would decline in 2012. Bogusevic experienced almost a 100 point decline in BABIP; Paredes and Downs had more than a 100 point decline in BABIP. The BABIP over-performers in 2011 suffered a sharp decline in BABIP.

Lee, Barmes, Sanchez, Altuve, Schafer, Towles, Corporan, Johnson, and Quintero posted BABIP lower than x-BABIP, suggesting that their BABIP might rebound in 2012. Towles and Sanchez drop out of this comparison, since they were minor leaguers in 2012. Of the remaining players: Lee, Schafer, and Quintero posted lower BABIP in 2012; Barmes, Altuve, Corporan, and Johnson posted a higher BABIP in 2012. Lee, Schafer, and Barmes had small 2012 BABIP differences from 2011. The results for BABIP underperformers, alone, is inconclusive. However, taking under and over performers together, the x-BABIP predicted the direction of BABIP change in 7 of 12 cases.

2012 x-BABIP

In 2011, I used the Hardball Times x-BABIP calculator. For this exercise, I will use the Fangraphs x-BABIP calculation. The formulas are different, and I'm not saying that the Fangraph method is better. This is a convenience on my part, since Fangraphs' Eno Sarris provided a compilation of x-BABIP for 2012 batters with at least 300 at bats.

The Fangraphs 2012 x-BABIP article is here. Just for those who want Justin Ruggiano back, he had the highest BABIP in excess of x-BABIP in the major leagues; tread with care in gambling on Ruggiano's performance in 2012. The only two BABIP over-performers among 2012 Astros' hitters were Chris Johnson and J.D. Martinez. Johnson, of course, is no longer with the Astros. J.D. Martinez had an actual BABIP of .290 compared to x-BABIP of .284. This is somewhat disappointing to me, since I would have hoped that the drop-off in Martinez's hitting would have been explainable by BABIP. Not the case, though.

I pasted the information regarding Astros' hitter BABIP under performance from the article below.

(Player, BABIP, x-BABIP, difference)

Maxwell .292, .304, .012

Altuve .321, .334, .0128

Lowrie .257, .293, .0357

Greene .292, .344, .0502

Bogusevic .257, .330, .0734

We should be encouraged that the Astros' three best hitters, Maxwell, Lowrie, and Altuve, under-performed their BABIP, implying that they achieved their offensive performance despite some bad luck in the BABIP Department. Tyler Greene had a large gap between his BABIP and x-BABIP. One can hope that this means he will move in the direction of a higher offensive output in 2013. Note that Bogusevic was one of the biggest under performers of x-BABIP in the major leagues.

The Fangraphs article calculated x-BABIP for hitters with 300 plate appearances. I calculated x-BABIP for some of the Astros' hitters with less than 300 plate appearances, with the obvious caveat that they are based on small samples. Jason Castro has the largest sample, falling short by only a few plate appearances.




























Again, all of these smaller sample size Astros hitters under performed their x-BABIP, implying the liklihood of reverting to a higher BABIP in the future. In another thread someone asked if I had calculated a x-BABIP for Dominguez---well, here it is, and it suggests better potential than the BABIP predicted by the Bill James system. On the other hand, Dominguez's sample size is so small that perhaps we shouldn't read much into it. Jason Castro's sample is more reasonable, and his 2012 x-BABIP is encouraging.

Too Much BABIP Under-performance?

The large number of BABIP under-performers raises some questions to me. Perhaps the Astros were just unlucky? Possible. But could there be other explanations? Does Minute Maid Park suppress BABIP? I'll discuss that in a minute. Is the Fangraphs x-BABIP formula biased toward under-performance? I don't know. We may have to wait for next year's actual performance to get a better read on the formula. Another possibility--not something we like to consider--is that some of the Astros' hitters do not have major league hitting ability--and, therefore, BABIP under-performance reflects lack of talent.

All of the data I have reviewed indicates that Minute Maid Park is slightly above average for BABIP. As additional evidence of this, the Astros team BABIP is higher at home than on the road during 2012. And this is also true over the 4 year period ending in 2012. Therefore, I doubt that MMP suppresses the Astros' hitters BABIP.