Statistical Analysis: What is BABIP?


A term we hear a lot about when it comes to statistical analysis is BABIP. But what is BABIP, and how can it be used to help determine things about a player?

I had planned on writing about what I know about BABIP, but after reading this article, it is apparent I know less than I thought I did. So instead, I’m just going to suggest that if you are interested in this, you read this article by Tristan Cockcroft from ESPN’s Fantasy Draft Kit. It’s an excellent primer on the topic, and I’m not sure I honestly could say it any better or really add that much to it.

My biggest thing with BABIP is that it, like nearly all other statistics, don’t tell the whole story, but can help to give you an idea of something to look at when making distinctions about players. Let’s look at the top 5 and bottom 5 players in BABIP, and see what (if anything specific) we can discern about them.

Leaders from Fangraphs.com for 2009 season:

David Wright (.394 BABIP) – Wright hit .307 last season, which is well within his range of performance in the past. His BABIP was a bit higher than it had been in the past, previously ranging from .321 to .356 in the previous 4 seasons. With him, I am not entirely sure I am concerned about this, as he also saw a substantial drop in his home run total, and as a result would have had more balls in play. 10 additional homeruns (to bring his total for the season to 20) would have dropped his BABIP to .376, which while still higher than any previous season, would have been closer to the range he had hit in previously.

Ichiro Suzuki (.384 BABIP) – Ichiro hit .352 in 2009, which was one of his highest averages in his career. For him though, his range of BABIPs since arriving in 2001 leads me to believe that while he may have been slightly lucky, it was not that far out of his range of expected numbers. His BABIP range since 2001: .316 to .399

Hanley Ramirez (.379 BABIP) – Hanley hit for his best batting average to date, posting a .342 batting average in 2009. He had hit over .300 in each of the previous 2 seasons, and posted BABIPs from .329 to .353. There may be a little luck in there, but I think it would require more investigation into Hanley specifically to see if there is something else in there that helped him in 2009.

Joe Mauer (.373 BABIP) – Mauer had his best season to date, posting a .365 batting average. Mauer has never posted a batting average for a full season under .293, and as a result his BABIP has also never dropped below .319 during that time. While .373 was his highest BABIP so far, he has consistently posted BABIPs over .320, and seems unlikely to see a particularly large regression in 2010.

Joey Votto (.372 BABIP) – Votto completed only his 2nd full season in 2009, and improved his batting average by 25 points from his 2008 season (.297 to .322). However, his BABIP spiked from .328 to .372. While I don’t necessarily think he’s going to drop off the face of the earth for batting average, I could see him potentially regressing back closer to .300 than to .320. Another player who may have other factors playing into his statistics that aren’t as easily seen.

Bottom 5 (Regulars only):

Ian Kinsler (.241 BABIP) – Kinsler hit .253 for the season overall, and had posted BABIPs of .304, .279, and .334 in his previous 3 seasons. For me, I would think that he was probably at least a bit unlucky last season, as he was 30 points below his career low of .279. When he returns to the field of play, I could see a rebound back toward the .270 range for his batting average as his BABIP gets closer to the .300 range he had been averaging.

Carlos Pena (.250 BABIP) – Pena hit .227, which was low even for him. In his previous two full seasons, his BABIP had been .297 and .298 respectively. The part that isn’t seen as easily is the fact that in those two seasons, his batting average was .282 and .247. So while he also appears to have been a bit unlucky, it is hard to discern which of the two batting averages is more likely to be the one you’ll get from him.

Jimmy Rollins (.251 BABIP) – Rollins hit .250 last season, which was down from his career average of .275. Over the 6 seasons prior to 2009, his BABIP had never been below .281, and his batting average below .261. This is a player who has shown for the most part a specific range of what can be expected out of him, and should rebound this season as well.

Yuniesky Betancourt (.256 BABIP) – Betancourt hit ,245 last season, but had previously shown himself to be able to hit .280-.290. During those same seasons, his BABIP had been between .289 and .308. Another player who may have been a bit unlucky last season at the plate.

Aubrey Huff (.260 BABIP) – Huff hit .241 last season, well off of his career average of .282. His BABIP range doesn’t necessarily tell us everything about him though, as he has varied widely over the previous 8 seasons, ranging from .267 to .315.

Overall, I think that BABIP can help you to look at whether a player may be due for a regression or an improvement, but it needs to be taken with a grain of salt. Over time, players will generally stay within a specific range of performance, and if that performance is high, BABIP may not tell you anything of use.

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