Author's note: This story uses math. Whenever an advanced statistic is used, please refer to the hyperlinked Fangraphs Glossary entries. I'll do my best to explain what each number means, but the glossary is really easy to read. If you're uncomfortable with the numbers, check it out.
A lot of folks have been frustrated with how the bottom half of the batting order has been performing. You can't swing a dead cat in the comments section without seeing complaints about Delmon Young, Brennan Boesch, Jhonny Peralta orAlex Avila. In some cases (Young and Boesch) the complaints are warranted, but it's a bit unfair to lump in Peralta (who has a .322 wOBA at shortstop, good for seventh best at his position) and Alex Avila in with the two disappointing corner outfielders. While I have looked at Jhonny Peralta before (see here), Alex Avila deserves some of the same attention.
In particular, there are a few questions about Avila, the biggest being his power outage. Avila's Isolated Power (a way to measure raw power without the influence of batting average) has dropped some 60 points from last year and 30 off of Avila's career average. There are other problematic signs too; Avila's average has dropped some 35 points since last year. Like with Peralta, the answer likely lies in the batted ball data.
First, let's take a second to put Avila's offensive production into context. As of Aug. 14, Avila is hitting .261/.364/.408 (BA/OBP/SLG) with a wOBA of .340. (For those of you not familiar with wOBA, imagine if on-base percentage accurately valued walks, homers and all other types of hits. wOBA takes all these types of hits and weighs them according to the run production each one produces.)
For all the complaining people seem to do about Avila, it is important to remember that his wOBA puts him at seventh among catchers with at least 300 plate appearances, ahead of such stars as Carlos Santana, Mike Napoli, Matt Wieters and Brian McCann. A good chunk of this is a function of Avila's stellar on-base percentage of .364, which is driven by a walk rate of 14.1% (fourth highest among catchers with at least 300 plate appearances). But Avila's patience at the plate is only one half of the story. His batting average and Isolated Power are still lagging.
Let's take on the easy question of batting average first. Those of you who read my posts and comments on a regular basis know that I love using BABIP, or batting average on balls in play. Oftentimes, fluctuations in batting average from year to year are due to changes in BABIP, and in Avila's case this is what happened from 2011 to 2012. His BABIP has dropped from .366 in 2011 to .332 in 2012- a fall of almost 35 points exactly. Hence, it's probably easy to chalk up the change in batting average to random variation.
What's also interesting to note is that Avila has had shockingly consistent batted ball data in the major leagues. While his BABIP has varied from 2009-2012, his xBABIP (expected BABIP, which we can predict based on batted ball data) has consistently fallen around .330 (Avila's xBABIP is currently at .345, due to a really high LD rate). This actually explains how Avila can put up respectable batting averages while striking out in almost a quarter of his plate appearances: he hits line drives at a higher than average rate (career average of 22.2% of balls put in play are line drives). It also gives me the impression that Avila has been consistent in terms of performance, even if the results haven't always been there.
Avila's line drive rate, in conjunction with the rest of his batted ball data, can also help us answer the question of Avila's power outage. This year, 25.5% of the balls Avila puts into play are line drives, 46.5% are ground balls and 28% are fly balls. Compared to league averages (20% line drives, 44% ground balls, 36% fly balls), Avila is not hitting the ball in the air nearly as much as his peers. This indicates to me that Avila just isn't hitting the ball in a way that would make it over the fence.
Let's examine Avila's HR/FB rates to confirm this. For his career, Avila has a HR/FB of 13.1, which is a bit above average. Currently this season, he has a HR/FB of 12.5%, which is close to his career average. Last season, when Avila hit 19 home runs, he had a HR/FB rate of 13.8% but 40.5% of the balls he put into play were flyballs (at the expense of grounders- his ground ball rate was a mere 37.8%, which looks to be an outlier).
Avila's doubles pace is close to last year's, and while he is slightly behind in triples, the difference in Isolated Power is almost certainly due to the drop in his home run rate. This leads me to conclude, in turn, that Avila's low Isolated Power is due to a drop in his flyball rate. As his batted ball data regresses and as Avila hits the ball on the ground more, his home run rate will drop. Of course, the 28% fly ball rate is a bit low for Avila, who has a career flyball percentage of 36%, and so it is certainly possible as Avila hits more flyballs that he'll also, in turn, hit more home runs.
In conclusion, Alex Avila does not deserved to be compared to hitters like Brennan Boesch and Delmon Young. While he has regressed from last season, he still has excellent offensive upside and provides great offensive value even with a bad fly ball rate sapping his power. The best news is that Avila is still young and cost controlled. Expect him to maintain a batting average around .270, an on base percentage around .370 and perhaps a spike upward in the power rate.