A New Update for DRC+ on Baseball Prospectus

A few eagle-eyed readers alerted us to an anomaly in our 2024 DRC+ values, whereby Luis Arraez, who was rating only slightly above average in our deserved equivalent metrics (dAVG, dOBP, etc.), nonetheless was rated in the 140 range by DRC+. Something was amiss.

We have tracked down the bug and squashed it. In short, one of DRC’s features is that it distinguishes between single and multiple out contributions, crediting pitchers (and punishing batters) who generate ground balls at unusual rates, thereby creating elevated potential for (and more likely deserving) multiple outs. The math to compute weights for single- and multiple-out balls in play was wrong, and as a consequence ball in play outs were not penalized enough. We have corrected the error.

The effects were as follows:

For players with more typical BIP rates, the differences are mild; the absolute weighted average change is about 5 points.
The further from average the batter’s ball in play out rate is, the more the batter’s DRC+ and WARP were affected. For the 2024 season, admittedly still in progress, we counted five batters with at least 250 PA who are affected by a win or more.
The players most affected are Arraez on one end (an extraordinary number of balls in play) and Aaron Judge on the other (an extraordinary number of balls not in play). The correction adds three wins to the latter and subtracts nearly two wins from the former.

With the fix applied, as of yesterday, 2024 Arraez is now rated at a 101 DRC+ for his stint with the Marlins and 105 for his stint with the Padres, and 2024 (Aaron) Judge rockets up from 172 into Bondsian territory with a 216, which certainly better reflects his Bondsian level of production.

We regret the error, and will push the fix out to other seasons as well, as they would be similarly affected, but as always we appreciate the heads up from our readers.

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