Christian Yelich and the BABIP question

The Miami Marlins are hoping Christian Yelich can continue his ongoing development and become another star player next to Giancarlo Stanton and Jose Fernandez. The early returns are positive, as Yelich won a Gold Glove award and carried a balanced approach in 2014 to a four-win campaign. If he can keep up that kind of performance, the Marlins would be very happy with his work.

Part of the reason why Yelich has been so good in his first two seasons has been his ability to just get hits. That has a good deal to do with his known bat skills; Yelich carried a reputation of a hitch-free, mechanically-perfect swing coming up through the minors. However, part of his success also has a lot to do with a high BABIP, which is well-known to be a volatile factor for getting hits. Yelich still has struggles with contact and strikeouts (21.8 percent rate career) and has minimal power, so he depends on hits on balls in play to get acceptable batting averages. So far, Yelich has hit a sky-high .363 on balls in play, a seemingly unsustainable mark.

BABIP is not as volatile for hitters as it is for pitchers, however. There is a chance that Yelich has a skillset that lends itself to higher marks in this department. What skills are those, and can we find players with similar profiles?

The Precedent

It is worth noting, as always, that the precedent for holding a huge BABIP like Yelich's is very low. From 2012 to 2014, only three players (Mike Trout. Yasiel Puig, and Chris Johnson) had a BABIP higher than Yelich's among qualified big leaguers. Only 10 ballplayers posted a mark above .350. That would be in a cohort of 223 players, meaning that the we are talking about maintaining a mark equivalent to the best four percent of baseball. Suffice to say, this is not easy.

If we lower our expectations a little bit, it still leaves us with a tough goal to reach. Steamer projects a .329 BABIP for Yelich this upcoming year, which appears to be the lowest projection among the major systems. Maintaining a .330 or better mark is something only 41 Major Leaguers did since 2012; that represents the best 18.4 percent of the game. To get a sense of how tough that is, the 41st-best batting line in the game in that time span was something like Justin Upton's .271/.350/.462 line, which was good for 24 percent better than the league average.

Pop-up Prediction

This establishes the challenge for Yelich. However, we know one skill that Yelich has that has helped him excel in this department. No, it's not speed, which is what is most commonly discussed when we discuss beating BABIP regression. For Yelich, this is the skill of avoiding popups. Last season, Yelich hit his first infield fly ball in 933 career plate appearances. In that same time frame, Pitch F/X has classified only four of his balls in play in total as "popups," infield or otherwise.

The advantage of this clear. Popups and infield fly balls are balls in play, but they function more like strikeouts; they are converted into outs nearly 99 percent of the time. Most players have a decent number of those types of balls in play in their profile, giving them automatic outs in their BABIP. In fact, the league averages a rate of around nine to 10 percent.

Yelich so far has been one of the few who have not been vulnerable to this issue, but he is not alone. Yelich's 1.3 percent infield fly ball rate (infield flies per fly ball) is impressive, but it is not even the best mark in baseball since 2012.

You can see that the players with the fewest popups in the game appear to also have universally above-average BABIPs. Only Howard is lacking the kind of BABIP that we are looking for in Yelich. In addition, many of those other players seem to have similar skillsets, with a higher ground ball rate and line drive marks above 20 percent, all leading to even fewer popups and more chances at solid hits. You can compare overall popup rates via Pitch F/X for Yelich versus the five above names.

You can see that Yelich is actually ahead of the general pack in terms of overall lack of popups, infield or outfield, in all of baseball. Overall, however, the effect of avoiding popups seems pretty clear in terms of allowing for higher batting averages on balls in play.

How sustainable is this effect? A linear regression of 2011 to 2013 data for the 201 qualified players who then recorded at least 100 plate appearances in 2014 showed that about 41 percent of next year's infield fly ball rate is predicted by the previous three-year infield fly ball rate. The guys at the lower end of the spectrum, however, held pretty firm for the most part. Only three players with a 2011 to 2013 infield fly ball rate of less than five percent posted a 2014 rate greater than five percent, and one of those was the outgoing Derek Jeter.

If we presume that this assumption would hold well for Yelich, we can predict a 2015 infield fly ball rate of 6.1 percent according to a league average of 9.5 percent. The average BABIP of a group of similar players would be .312. However, if you use the trend line from the regression to estimate future BABIP for Yelich, you get a 2.8 percent mark. An average of those players leaves you at .332, which is more in line with what some of the expectations show.

An even better cohort would be among players like Kendrick who hit high ground ball and low fly ball totals, leading to very low number of overall popups. There is a chance that that cohort yields even better results. It is overall still too early to see if Yelich's lack of popups is a true skill, but we can come out reasonably happy with his chances of at least repeating a high BABIP in the .330's based on this analysis, and that would fall in line with the projection systems. That should keep his batting line intact even with his mediocre strikeout numbers, If this skill continues, it will be even more proof of the odds that Yelich can keep up his high marks.