Dissecting Brennan Boesch


Possibly the biggest story of the 2010 Detroit Tigers was the meteoric rise and subsequent fall of outfielder Brennan Boesch. Called up in late April, Boesch wasted little time claiming an everyday day role for the Tigers, be it as the left fielder or as the DH. We all know the story by now. Boesch hit .342 in the first half of the season. He slugged 12 home runs, had 49 RBI and was widely viewed as an all-star snub when he was left off the roster for the mid-summer classic.

The second half saw Boesch not only return to earth, but come crashing to depths below. Boesch’s second half line included just two home runs, 18 RBI, and a batting average of .163. His average was nearly 200 points below his first half mark, his on base percentage sank 160 points and his slugging average dropped over 370 points, all this resulting in an OPS that was .990 before the break and just .458 afterward. But what caused this sudden and dramatic demise?

In the months of May and June, when he was at his absolute best, Boesch posted a combined .340/.390/.612/1.002 line. He stuck out just 19.5 percent of the time he reached the plate and walked 8.2 percent of the time. He benefited from a BABiP of .384 during those two months. In May, Boesch posted a line drive rate of 17.6% a ground ball rate of 41.2%, which was identical to his fly ball rate. In June, Boesch posted a similar LD rate at 17.3%, but saw his ground ball rate climb to 48.1% while his fly ball rate dropped to 34.6%. In each month, a high percentage of his fly ball sailed over the fence, doing so 10.7% of the time in May, but an amazing 28.6% in June.

As the season progressed, Boesch fell into a slump in July, posting a .209 average and .564 OPS. This can be seen in his line drive rate more than anywhere else, which fell to 10.7%. Additionally, Boesch was no longer carrying balls over the fence, hitting zero home runs in the month. He posted a BABiP for the month of .253.

From July to August, Boesch’s line drive rate improved to 17.9%, actually his best month of the year. His groundball rate stayed steady, and his fly ball rate decreased. This should have lead to a better month, but Boesch hit just .185 in August with a .531 OPS. His continued decline in August came despite the fact that he had seven extra-base hits in the month versus just four in July. Again, looking at BABiP, Boesch shows another drop off, this time to .231. As the season progressed, his luck got worse.

At this point in the year, I think we can get a good feel for the type of hitter Boesch is, really. In three of the four full months he was in the lineup (May-August), his line drive rate was between 17 and 18 percent. His ground ball rate was between 41 and 49 percent in all four months (three between 46 and 49 percent, and his fly ball rate varied between two months at around 35 percent and two months at roughly 42 percent. The major differences in his production can be attributed to his home run rate and his BABiP.

The final months of the year (September and October) are combined due to the small number of October games. In this segment, Boesch saw his line drive rate fall to 13.8%, but his ground ball and fly ball rates stayed steady, coming in at 48.3% and 37.9%, respectively. Again, BABiP was the culprit to his poor numbers. Boesch totaled just a .186 average and .489 OPS for the month and suffered from a season-worst .224 BABiP.

When comparing his season totals to his minor league stats, you see a guy who actually was pretty similar overall to what he probably should have been. In his four minor league seasons, Boesch had BABiPs of .325, .297, .298, and .309. In his first big league season, he came in at .297 for the Tigers. His strikeout and walks rates were actually fairly close as well. What this tells me is that luck played a much larger role in his demise during the season’s second half that I had thought.

Boesch benefited from an extremely lucky batting average on balls in play in the first half of .384, but after the all-star break, his BABiP was only .201. So what does that mean going forward? To me, it means that Boesch isn’t the hitter he showed us in the first half, but he’s far from the hitter he was in the second half. Considering that his BABiP of .297 was pretty close to league average (and in line with his minor league track record), I’d say that Boesch’s season line of .256/.320/.416/.736 is probably about what you can expect him to be as a major leaguer. Sure, he’s still young enough that you could expect an uptick thanks to maturity, but his 99 OPS+ (almost exactly league average) shows that that’s probably what Boesch is as  hitter at this point in his career. But being a league average hitter as a rookie is certainly nothing to scoff at.

What it also tells me is that because of his “challenged” defensive play, Boesch probably isn’t good enough to be considered a regular player on a good team. His offensive production would have to make up for his defensive shortcomings to play regularly in the field and he’d have to hit more than he does to be a regular DH. In other words, the Tigers were right to re-sign Magglio Ordonez to play right field. They’d probably do well to trade Boesch if they can get find a GM who thinks Boesch’s first half was more than the mirage it appears to have been.

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