Detroit Tiger Cubs: Brennan Boesch

This is the first in an intended series on the 2010 Detroit Tigers rookies.  Next up will be Austin Jackson.

The 2010 Tigers offense has been just that: highly offensive (Get it?  It's a pun!).  While Miguel Cabrera has been a beast all year, the rest of the lineup has either been inconsistent or just plain terrible.  Austin Jackson is currently in an extended slump.  Johnny Damon started off slowly, then heated up, and then cooled off again.  Guillen has spent most of the season on the DL.  Sizemore, Everett, Raburn, Avila, Laird, Inge, and Kelly have been all kinds of terrible.  One of the non-offenders has been rookie Brennan Boesch.  Already a fan favorite, he has also drawn skepticism from the prospect watchers and sabermetricians among us for his seeming inability to take a walk, his propensity for swinging at junk pitches, and his lack of a solid minor league track record (before 2009, that is).  So far this year, he is hitting .338/.384/.626 with 7 HR and 29 RBI in 38 games.  Simply put, Boesch has been the second best hitter in the Tigers lineup.

The question: Can he sustain this production?

The Minors

Boesch was taken in the third round (82nd overall) of the 2006 draft from the University of California, Berkeley.  While he was considered a great talent, many scouts noted his stiff swing as a clear red flag.  Debuting with the Oneonta Tigers in 2006, Boesch hit .291/.344/.435 in 70 games.  At West Michigan (2007) and Lakeland (2008), Boesch failed to reach even a .700 OPS as a regular.  The worst news, for someone drafted on the strength of his plus power potential, was that Boesch only managed double-digit home run numbers once in his first three seasons (he hit 10 at West Michigan in 513 AB).  By the end of 2008, it seemed likely that Boesch would be nothing more than organizational filler.

In 2009, Boesch found his long-awaited power stroke, hitting 28 home runs in 527 AB (though some of this new-found power was probably due to Erie's homer-friendly park).  Despite his prodigious power (.235 ISO), Boesch only mustered a paltry .318 OBP, due to a walk rate of less than 6%.  In addition to a tiny walk rate, Boesch's strikeout rate increased at each level, from 14.4% at Oneonta to 24.1% at Erie.  While the walk and strikeout rates make it hard to call 2009 a true breakout year, Boesch certainly took a step in the right direction.

On the strength of his 2009 season, Boesch resuscitated his status as a legitimate Tigers prospect.  While he didn't make Baseball America's or John Sickels's lists, Fangraphs named him as the system's eighth best prospect and Kevin Goldstein rated him as the Tigers' fifteenth best prospect.

After a torrid start in AAA to begin the 2010 season (.379/.455/.621 in 15 games), Boesch was called on to fill the large power gap in the Tigers' offense.

The Majors

If you are a regular on this blog, or even a casual Tigers fan, you don't need me to tell you that Boesch has responded to his promotion in a big way.  He has provided both the badly-needed lefty power bat and the badly-needed protection for Miguel Cabrera.  How could someone with such an uninspiring minor league career burst onto the scene so dramatically and suddenly?  And, more important, can he keep it up?

As noted above, one of the knocks on Boesch has always been his stiff swing, resulting in a swing so full of holes that you could (as David Tokarz would say) drive your Boesch Bus right through it.  Despite these concerns, however, Boesch has managed to make contact at only a slightly below average rate (79.1% compared to MLB average of 81.1%).  While he has been making contact at a passable rate, those critics who point to Boesch's propensity for swinging at junk pitches are justified: he has swung at 46.5% of pitches outside of the zone (compared to MLB average O-Swing % of 28%).  To put that in further perspective, Vlad Guerrero's career O-Swing percentage is 38.9%.

Given Boesch's below average contact rates and above average O-Swing%, it would seem highly likely Boesch is racking up a huge number of strikeouts.  Surprisingly, his strikeout rate (SO/AB) is only slightly worse than average (22.3% compared to MLB average of 20.4%).  It would also seem likely that Boesch would not be drawing many walks.  In this case, he is also below average, posting a walk rate (BB/PA) of just 6.6% (compared to MLB average of 9.0%).

Considering these pedestrian peripherals, it is hard to see how Boesch could be as successful as he has been, and it seems likely that he might simply be getting lucky.  Indeed, this does turn out to be the case.  He currently sports a BABIP of .392, though his expected BABIP (xBABIP) is only .297.  That is a pretty hefty difference, and when his BABIP inevitably regresses, his lofty offensive numbers will regress with it.  Since much of his value so far has been derived from a high batting average (.338) that has offset his low walk rate, it is hard to imagine him remaining this effective throughout the whole season. 

As has been noted in his scouting reports, however, most of his value will be derived from his big power, which seems legitimate.  He currently has a 14% HR/FB ratio, and while this could also be luck driven, it seems likely that he will continue to hit HR at an above average rate (though without any previous major league track record, this cannot be said conclusively).

Conclusion

It seems highly unlikely that Boesch will remain this productive throughout the course of his career, or even this season.  Considering his relatively unimpressive minor league numbers, his luck-driven batting average, and his combination of high strikeout/low walk rates, I would be VERY surprised if he manages to be anything more than an average MLB hitter over a sustained amount of time.  Ultimately, I expect him to be a similar hitter to Marcus Thames: lots of strikeouts, lots of home runs, and not enough walks.  That said, Boesch has three things that Marcus completely lacks: a decent glove (UZR has him as a little below average), decent speed, and a left-handed bat.  Even if his production declines, I still suspect that these three things will earn him plenty of chances to be an effective big league regular.

All stats taken from www.baseball-reference.com and www.fangraphs.com