We recently took a look at the Tigers team defense through the eyes of David Pinto’s Probabilistic Model of Range. As Pinto wraps up this season’s numbers, he calculated the PMR behind each pitcher. Not much went right for Nate Robertson this year, and it is little surprise that his woes were reflected in the PMR numbers as well.
The table below is a combination of Pinto’s PMR work and batted ball data from Fangraphs.
Nate Robertson had the 7th lowest rate of balls in play converted to outs in Major League baseball. Now Robertson wasn’t particularly unlucky – at least in regard to his fielders letting him down. His defense only made 2 fewer plays than expected behind Robertson. Robertson also posted one of the lowest expected DER’s in baseball as well.
What is unexpected is why that rate is so low. Looking at his batted ball stats, they aren’t remarkable in any way. His line drive rate isn’t high, his infield fly rate isn’t low. His ground ball and fly ball rates are consistent. Yet his expected DER is a recipe for disaster. Is it that Robertson was especially unlucky in that a disproportionate number of balls were hit to locations where nobody could get to them (save the “over-the-fence” jokes, those aren’t in these stats).
Meanwhile, Armando Galarraga was on the opposite end of the spectrum. He had a high expected DER, plus his defense helped him out to the tune of 16 plays. Kenny Rogers gave up a fairly high line drive rate, so his struggles aren’t at all surprising. Justin Verlander was hurt by his defense to the tune of 4 plays, but hardly was that the main source of his struggles.
But back to Robertson, I don’t know what to make of the data. Sometimes it feels like a cop-out to chalk things up to luck, and I saw Robertson struggle – especially in the second half. His peripherals did slip with Nate fanning a few less hitters and walking a few more, but those shifts paled in comparison to the .343 batting average on balls in play. If he was giving up line drives all over the park, it would be easier for me to chalk things up to a lack of stuff. That wasn’t the case. It truly does seem like the opposition managed to “hit-em-where-they-weren’t” with remarkable consistency last year.