Replacing One Durbin With Another

In one of my first posts here at Fangraphs I discussed some odd name similarities amongst players on the Phillies. One I did not mention was that, since 1909 there have only been two major leaguers with the last name of Durbin—JD and Chad—and both are currently on the Phillies; incidentally, they are not related either. JD is pitching in AAA this year but Chad signed a 1-yr/900k deal to pitch for the big club. Through the first two months this low-risk signing has definitely brought with it high reward.

In 23 games, Durbin has a 1.80 ERA, 3.46 FIP, and 1.20 WHIP. He has pitched in 35 innings, surrendering just 28 hits, only one of which was a home run. His walks and strikeouts are a tad suspect, 14 BB – 21 K, but opponents are hitting just .221 against him; additionally, despite a career BABIP ~.300, his current mark is .258. Not many runners have been getting on and 86.5% of those who do have been stranded.

What’s different now from a year ago? For starters, his rates of balls in play have changed. Compare his LD/GB/FB:

2007: 15.6% LD/44.0% GB/40.5% FB
2008: 21.4% LD/42.7% GB/35.9% FB

The grounders are very similar but he has traded in a reduced percentage of flyballs for an increase in line drives. A percentage of line drives like that, via the xBABIP tool of LD% + .120, should in theory produce a BABIP close to the .334 range; Durbin’s .258 is much lower. Though the xBABIP is not a good predictive tool for pitchers, mainly because the LD% is not stable, it can be effective when retrospectively analyzing a pitcher’s results. In Durbin’s case it appears he has either been lucky so far or, as The Professor at Rays Index recently hypothesized, the lower BABIP for certain pitchers could be a byproduct of enough movement to make the batters miss the sweet spot.

Durbin has increased slider usage by 12%, meaning 85% of his pitches are fastballs and sliders. As a reliever, conventional wisdom chimes in that he should be able to get away with a lesser repertoire. Whatever he’s doing is working, though, as his 10.15 BRAA ranks 7th amongst all relievers in the game, and 4th in the National League.