How Did Mark McGwire Age Compared To Previous Sluggers? (Part 2)

In Part 1, I compared his and all the previous players with 400+ HRs in how their SLG from age 31-37 compared to their SLG from when they were under 31. McGwire came out first in this ratio. Here, I am following a suggestion made by Walt Davis who said "I'd be interested in comparisons of on-contact SLG, ISO and OPS relative with league average..." I use the on-contact ISO. (If I get a chance I will add the on-contact SLG-UPDATE: I just posted that, 2-4). ISO is isolated power and is usually SLG - AVG.

I took the neutralized stats for each guy from Baseball Reference (neutralized for parks and league averages). For contact, it was AB - K. Then I calculated each guy's extra bases (XB). The on-contact ISO then was XB/(AB - K). Again, the older rate was divided by the younger rate. McGwire had .575 at the older age and .350 at the younger age. Then .575/.350 = 1.64. Here is how they all came out:

McGwire 1.64
Stargell 1.21
Aaron 1.14
Mays 1.08
Dawson 1.03
Musial 1.02
Winfield 1.02
McCovey 1.00
Ruth 1.00
Williams 1.00
B. Williams 0.97
Schmidt 0.96
Jackson 0.95
Robinson 0.92
Evans 0.91
Gehrig 0.89
Killebrew 0.88
Mantle 0.88
Ott 0.87
Snider 0.86
Foxx 0.82
Murray 0.82
Mathews 0.81
Kingman 0.77
Banks 0.76
Yastrzemski 0.75

Here is the ranking for SLG on contact or TB/(AB - K). McGwire had .691 under 31 and .968 from 31-37. Since .968/.691 = 1.40, that is what McGwire gets.

Player Ratio
McGwire 1.40
Stargell 1.14
Aaron 1.05
Mays 1.04
Winfield 1.00
Schmidt 0.99
Dawson 0.99
Ruth 0.98
Musial 0.98
B. Williams 0.98
McCovey 0.98
Robinson 0.98
Evans 0.97
Williams 0.97
Jackson 0.96
Killebrew 0.93
Snider 0.92
Ott 0.92
Mantle 0.91
Gehrig 0.90
Foxx 0.89
Murray 0.87
Yastrzemski 0.85
Banks 0.85
Mathews 0.84
Kingman 0.83