A follow-up on BABIP: More on home runs, xBABIP and Odubel Herrera

On Dec. 26, I published a piece titled “The luck factor: How to maintain your BABIP and become a ‘gem.’” Before you read this, check that one out, because this article serves as a follow-up piece to that.

In short, I used the top BABIPs from 2017 to attempt to figure out which skills make the statistic — which is generally considered to be relatively unsustainable — sustainable. I found that about 70 percent of the players that ranked in the top 25 of BABIPs from 2017 had at least one of the “special” skills, and six hitters fell into multiple categories. Seven hitters did not make any list.

The article also generated lots of conversation on Twitter, and I hope to answer some of the questions that people had in the paragraphs below. So, really, this piece is for the readers. Enjoy.

A note on home runs

As I wrote in my original piece:

In the age of “elevate and celebrate,” I thought that hitters with a high fly ball rate might also have high BABIPs. I was wrong, and it conceptually makes sense why.

For the purpose of BABIP, home runs are not considered batted balls, since they leave the yard. So every time a batter celebrates a four-bagger, they aren’t helping their BABIP. And that also makes sense, too. There’s no chance for a fielder to make a play on a home run, so hitters should not get credit toward their BABIP for putting a ball into orbit.

A couple people had some responses to this:

To clarify for Steven Nathan, the reason home runs are not included is because BABIP loses its original purpose. The original purpose of BABIP is to determine whether more batted balls are falling for hits than we would expect. If a batter was to hit a lot of home runs, that’s them using their skill. There’s little to no luck involved.

Think about it this way, a blooper over the second baseman’s head might be caught by 10 out of the 30 second basemen in the league. If you happen to hit a blooper to one of the 10 that is able to catch it, that’s unlucky because you’d expect a similar ball to hand for a hit ²⁄₃ of the time in this example. But since home runs are, for the most part, indefensible, they shouldn’t be included in BABIP because then the stat loses it’s original purpose. This is true even despite the fact that they are technically batted balls.

And, in response to cwsoxfan, home runs are not inputted as outs. They are removed altogether, from both the numerator and the denominator of the BABIP equation.

I will admit, it would be interesting to see a BABIP stat with home runs included, although I’m not entirely sure what it would necessarily tell you in terms of usefulness. It’ll be something I look into in the future.

Some thoughts on xBABIP

Patrick Brennan brought up the possibility of looking into an xBABIP metric:

FanGraphs put together an xBABIP metric in May 2016, with an update coming this past February with shift data. In theory, that’s what I tried to do with my article: find skills that keep a player’s BABIP high. FanGraphs just put the numbers to it, which you can see here, though I couldn’t find information for the 2017 season.

Not to get defensive, but I think BABIP is one of the few times where generalizations might work better than an actual x-stat. Why? It’s because the correlation between xBABIP and a player’s actual BABIP isn’t that strong. FanGraphs’ most updated version of it only had an R-squared value of just around 0.5, which does not signify a strong correlation.

That’s why, at least I think, it might be better just to consider whether a player is in the top-20 percent of the league in one of those skills that I discussed to truly figure out whether his BABIP is at all sustainable. I could be wrong about that, but I do believe that the logic here makes sense.

What’s the deal with Odubel Herrera?

So, yes, I don’t know what’s up with Odubel Herrera:

Herrera:

• Doesn’t hit a ton of line drives
• Doesn’t hit the ball super hard
• Isn’t one of the fastest players in baseball

Yet, as Jason Mitchell points out, Odubel Herrera’s BABIP for the last three years is, in fact, “very high.” In 2017, Herrera’s BABIP was .345, and that was a career low. His career average is .359, and since he broke into the league in 2015, only three hitters have a better BABIP than him.

What gives?

I first considered Herrera’s infield hit percentage. He’s had a knack for turning infield ground balls into hits (while not having blazing speed), and that would be an automatic BABIP booster. That might explain his 2015 and 2016 BABIP numbers, as he ranked 13th and 1st in the Majors in infield hit percentage (percent of infield grounders that go for hits) in those two seasons, respectively. But in 2017, his infield hit percentage dropped, and he fell all the way down to 45th in the league in the metric, while keeping his BABIP up at .345.

So that can’t be it.

I could take the easy way out and say that Herrera had sustainable BABIPs in 2015 and 2016, while being lucky in 2017, but surely I can’t do that.

He may have used the infield hit percentage to boost his 2015 and 2016 BABIP numbers, but turned to a different skill in 2017 to keep it just as high. His hard hit percentage did see a two percentage point spike, but still, his average exit velocity wasn’t that much different than the league-average.

Herrera does have one other distinction about him that makes him different from just about every other hitter: he rarely pulls the ball.

Don’t get me wrong, Herrera does still pull the ball, doing so 30.8 percent of the time in 2017. That, however, is nine percentage points below the league average. This isn’t new for Herrera, either. He, in fact, has the ninth-lowest pull percentage among all qualified hitters since breaking into the league in 2015.

You may be thinking that pulling the ball creates the most hits because batters can generate the most power pull-side, and that is true. . .for most. The league-average batting average on pulled balls is .344, compared to a .343 batting average for balls up the middle and a .316 batting average for balls hit to the opposite field.

Herrera is different. He hit .347 on pulled balls, above the league-average. But he hit .362 on balls up the middle and .403 (!) on balls hit to the opposite field.

These numbers actually fall fairly in line with what Herrera has done over the course of his entire career:

Bingo. I am fairly certain now that Herrera’s high BABIP comes from exploiting an area of the field that he knows will result in the most hits. Most of Herrera’s batted balls go up the middle or to the opposite field, and these are also the areas where he has consistently generated the most hits.

Why is this the case? I don’t really know. It could be a multitude of factors, including but not limited to defensive positioning, ballpark factors or even his own swing mechanics.

Regardless, I hope that this piece answered some of your questions and provided more clarity on what BABIP is, how it works and perhaps another skill that allows hitters to be successful at maintaining it.

Odubel Herrera might be a BABIP gem after all.

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Devan Fink is a Featured Writer for Beyond The Box Score. You can follow him on Twitter @DevanFink.