In article <1180088407.062835.45...@q19g2000prn.googlegroups.com>,
 Lord Buckeye <l_buck...@yahoo.com> wrote:

On this subject here are some updated numbers I originally posted a
couple of years back, a chart of how frequently Aaron and Bonds hit home
runs relative the league in which they were playing, by age:

Age     Aaron HR% / league    Bonds HR% / league
20            1.05
21            1.48                1.67
22            1.47                1.65
23            2.63                2.29
24            1.60                1.58
25            2.27                2.76
26            2.74                2.24
27            1.99                3.75
28            2.90                3.38
29            3.15                3.39
30            1.92                2.35
31            2.36                2.85
32            2.93                2.68
33            3.25                2.32
34            2.95                2.96
35            3.60                3.01
36            2.90                4.58
37            4.55                3.84
38            3.52                3.76
39            4.35                3.75
40            3.05                4.06 (in only 14 games)
41            1.15                2.21
42            2.16                3.92 (through 5-24-07)

Normalizing their home run rates to the league is of course an attempt
to reduce the effect that external factors would have on the comparison,
such as the changes in the height of pitching mounds, the size of the
strike zone, the size of the ballparks, etc. However, this normalization
doesn't adequate reduce the effect their home ballparks may have had.

From ages 32 to 40 Aaron played his home games in Atlanta-Fulton County
Stadium, where he hit about 33% more home runs than he did on the road,
a difference that's entirely consistent with the overall effect of the
ballpark on home run rates. So I think it makes sense to adjust Aaron's
numbers for ballpark effects in those years.

On the other hand, since Pac Bell/SBC/ATT&T Park opened Bonds has hit
152 home runs there while hitting 153 home runs on the road, so even
though the park depresses home run rates for most lefties I don't think
it's appropriate to apply ballpark adjustments to his numbers for the
sake of comparison.

So, for the key years from ages 35 to 39, here are Aaron's adjusted
numbers along with Bonds' raw numbers. Aaron's late-career power surge
is still comparable to Bonds':

Age  Aaron adj HR% / league   Bonds HR% / league
35            3.13                3.01
36            2.52                4.58
37            3.97                3.84
38            3.06                3.76
39            3.78                3.75

Another way to put this is to say that the amazing rate at which Bonds
hit home runs relative to the league at age 36 (4.58) is nearly
identical to the rate at which Aaron his home runs relative to his
league at age 37 (4.55), neither one of them having achieved so high a
rate earlier in their careers. Conventional wisdom says that Aaron
required only the aid of a friendly home ballpark to achieve that feat,
while Bonds required the aid of the clear, the cream, the three witches
from Macbeth appearing in the forms of Anderson, Conte, and Valente, and
maybe also that guy Robert Johnson met at the crossroads.

Anyway, there are the numbers.