Hi everyone. Relatively new to WhatIf, but a long-time baseball fan and sabermetrics afficionado. I've been toying around with the available stats in Excel, and put together a multiple regression analysis using $/IP as the dependent variable and ERA, ERC, OAV, WHIP, HR/9, BB/9 and K/9 as independent variables (all using the
normalized stats as given). The analysis yielded the following:
R-square = .871412 (high, these factors unsurprisingly strongly predict the player's price)
Coefficients:
Intercept = 74522.56 (p = 0)
ERA = -91.6313 (p = 9.06E-06)
ERC = 2598.706 (p = 4.2E-283)
OAV = -195551 (p = 0)
WHIP = 82.41085 (p = .871955)
HR/9 = -7724.62 (p = 0)
BB/9 = -2747.95 (p = 0)
K/9 = 371.6703 (p = 0)
Because the variables have different scales, the coefficients themselves aren't useful, but the signs are meaningful (as are the p scores). The conclusion that WHIP isn't very useful when controlling for OAV and BB/9 isn't very suprising.
What I can't figure out, though, is why the coefficient for ERC would be positive. This suggests that when these other variables are controlled for, a higher ERC makes a player more valuable (whereas common sense would suggest a lower component ERA would be more valuable).
If WhatIf uses
Bill James' definition of ERC, then:
ERC = (((H + BB + HBP)×PTB)/(BFP×IP))×9 - 0.56
where H is
hits, BB is
bases on balls (walks), HBP is
hit by pitch, BFP is
batters faced by pitcher, IP is
innings pitched, and PTB is defined as:
PTB = 0.89×(1.255×(H - HR) + 4×HR) + 0.56×(BB + HBP - IBB)
where HR is
home runs, IBB is
intentional walks, and others are as above.
Do people like pitchers who hit batters more? This would be my conclusion, since HBP is the one component of ERC not controlled for in this regression.
Anyone know why this might be the case?