Four Factors: Brennan Boesch

It seems like there was a warm response to my four factors for evaluating hitting that I presented in this post on Martin Prado last Friday. As such, I’d like to use it to take a look at a few more players. One player about whom I think these stats tell a particularly interesting story is Tigers rookie Brennan Boesch.

As a reminder, the four factors of hitting are BB%, K%, POW (XB/H), and BABIP. That is, walk rate, strikeout rate, power (as measured by extra bases per hit), and success on balls in play. I feel that these four statistics sum up extremely well four facets of hitting under which the batter has control.

Let’s take a look at how Brennan Boesch fares under these four measures.

Boesch, to date, has excelled in both power and success on balls in play, performing at a level nearly 130% of the league average in both factors. He’s slightly above average in strikeout rate and a bit below average in terms of walk rate. There’s no doubt that he has been excellent so far this season; his .426 wOBA is right between Joey Votto and Kevin Youkilis on the leaderboard – certainly impressive company for a rookie.

Of course, when a young player with no MLB track record posts these kinds of numbers over any significant period of time, we have to wonder if it’s sustainable. Simply due to the nature of regression, even if a player has ridiculous minor league numbers (which Boesch doesn’t), we would never expect a .426 wOBA to stay that high. What can we reasonably expect out of this extremely hot hitter as the season winds down?

Unfortunately, ZiPS doesn’t have a projection for him in the system. CHONE, however, in its July update, projected Boesch for a .259/.300/.438 line, worth about -7 runs per 150 games. That’s a marginally over replacement level player with average defense in the corners.

To see why CHONE is so down on Boesch, we need to look no further than the four factors. Take a look at how quickly each of the statistics involved here stabilize:

K%: 150 PA
BB%: 200 PA
ISO (presumably, POW would stabilize at a similar time): 550 PA
AVG: >650 PA

Boesch is only 267 plate appearances into his MLB career. For that reason, we can be relatively confident on his below-average walking ability and his above-average ability to avoid the strikeout. However, the two aspects of his game that have him at the top of the MLB leaderboards – power and balls in play – just simply don’t show themselves this early in a player’s career. Boesch showed solid power in AA (0.84 POW) but hasn’t ever showed the kind of BIP skills that would necessarily lead to a .384 or even a .320 BABIP in the majors.

Right now, it’s simply too early for us to conclude that Boesch is so much better than his minor league performance would suggest to even say that he projects as an average hitter going forward. He has certainly impressed in his time on the field in 2010, but his power and success on balls in play are likely to drop. Given the rest of his skills, he simply can’t maintain the elite hitting if this drop occurs. It’s certainly not impossible that this is just a breakout year for Boesch, but the Tigers shouldn’t act as if Boesch is another Miguel Cabrera in their lineup as they plan for the second half.