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Monday, October 01, 2007
The D’backs and WPA
Here’s the NL data:
Team OBP SLG O2PS sERA rERA ARI 0.321 0.413 0.968 4.23 3.95 COL 0.354 0.436 1.048 4.55 3.86 PHI 0.354 0.458 1.070 4.91 4.50 SDP 0.321 0.410 0.965 4.08 3.05 NYM 0.342 0.432 1.024 4.40 4.03 CHI 0.333 0.422 0.998 4.19 3.76 ATL 0.339 0.435 1.021 4.45 3.54 MIL 0.329 0.456 1.025 4.55 4.24 LAD 0.337 0.406 0.989 4.43 3.82 STL 0.337 0.405 0.988 5.04 4.07 HOU 0.330 0.412 0.983 4.71 4.69 WAS 0.325 0.390 0.952 5.11 3.80 CIN 0.335 0.436 1.016 4.86 5.13 MIA 0.336 0.448 1.029 5.58 4.05 SFG 0.322 0.387 0.944 4.24 4.12 PIT 0.325 0.411 0.973 5.00 4.80 AVG 0.334 0.422 1.000 4.65 4.09
That’s OBP, SLG, modified OPS, starter ERA and reliever ERA.
The modified OPS is 1.73*OBP+SLG. The league average of that is 1.000. It scales like OBP, so if you divide by 3, you get something that is OBP-ish.
We can convert the modified OPS, starter and reliever ERA into wins. To convert the OPS figure for Dbacks: (.968 - 1.000)*160-1.9. The 1.000 is the league average, 160 is a multiplier to convert OPS into wins, and -1.9 is to scale to WPA for NL hitters.
To convert the starter ERA: (4.46-4.23)*12+0.8. 4.46 is the NL ERA (or something close to it), 12 is the multiplier to convert ERA to wins, and +0.8 is to scale to WPA for NL starters. For relief ERA, change 12 to 6 and 0.8 to 0.4.
Here’s the expected WPA for each component (using the above conversions) and the actual WPA. eoWPA is expected offense WPA, oWPA is offense WPA.
eW-L is expected Wins minus Losses, and W-L is actual wins minus losses.
Team eoWPA esWPA erWPA eW-L oWPA sWPA rWPA W-L ARI -6.9 3.6 3.5 0.1 -1.2 2.7 7.5 9 COL 5.9 -0.3 4.0 9.6 9.0 -0.8 -0.1 8 PHI 9.4 -4.6 0.2 5.0 10.8 -3.7 0.9 8 SDP -7.4 5.4 8.9 6.8 -6.6 6.6 8.0 8 NYM 1.9 1.5 3.0 6.4 3.9 1.7 1.4 7 CHI -2.2 4.0 4.6 6.5 -2.2 3.4 2.7 4 ATL 1.6 0.9 5.9 8.4 0.0 -1.9 4.8 3 MIL 2.2 -0.3 1.7 3.6 1.5 -0.4 0.9 2 LAD -3.6 1.2 4.2 1.8 -5.0 -0.3 6.3 1 STL -3.8 -6.2 2.7 -7.2 -2.9 -6.9 6.8 -3 HOU -4.6 -2.2 -1.0 -7.8 -8.2 -2.5 2.7 -8 WAS -9.5 -7.0 4.4 -12.1 -9.7 -3.6 5.3 -8 CIN 0.6 -4.0 -3.6 -7.0 -0.8 -3.5 -4.7 -9 MIA 2.8 -12.6 2.9 -6.9 1.2 -13.2 2.0 -10 SFG -10.8 3.4 2.4 -4.9 -11.0 2.8 -1.8 -10 PIT -6.1 -5.7 -1.6 -13.4 -9.1 -4.7 0.8 -13 AVG -1.9 -1.4 2.6 -0.7 -1.9 -1.5 2.7 -0.7
So, how did the DBacks do it? They got 5.7 more wins out of their hitters than their hitting line would suggest, 0.9 fewer wins from their starters, and 4.0 more wins from their relievers.
The Cards and Astros were equally effective with the timeliness of their bullpen (+4 wins), while the Rox and Giants were just as ineffective (-4 wins).
No one approached the timeliness of their hitting.