Re: Bonds Responds
RB says:
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Except when we look at trend of the entire league before and after those changes, it doesn't increase...it decreases.....exactly the opposite of what it did in Hank's case, and exactly opposite of what you say you would "expect".
1962-1968 NL AB/HR: 45.1
1969-1975 NL AB/HR: 46.1
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AB/HR - National League
1965- 42.0
1966- 40.1
1967- 49.9
1968- 61.6
1969- 44.7 (expansion/rule changes)
1970- 39.5
1971- 47.7
1972- 46.4
1973- 42.6
So I would say the overall home run environment proved to be relatively neutral, outside of a couple outlier years. I guess the graph I pulled the other day is misrepresenting something.
But now lets look at the weighted park factors for Aaron. And yes, I understand PF isnt the best way to measure when talking about HR's, but I think it is usable. From what I understand this is average park factor weighted by number of at bats for Hank Aaron.
Year PF
1966 102
1967 99
1968 100
1969 100
1970 106
1971 106
1972 109
1973 108
Part of this is Fulton County Stadium. Starting in 1969 the Braves and their opponents hit HR's there at a 1.35/1 rate when compared to other parks. So that would certainly lead to a jump in the weighted park factor. And to a jump in home AB/HR.
The road rate is not as easily explainable. As RB pointed out, Aarons road AB/HR moved from 16.47 (1966-69) to 14.97 (1970-73), while the league numbers remained pretty steady.
Stay with me here, I think this could be interesting. As I mentioned earlier, there were 5 new stadiums built from 1969-71. 3 of them depressed offense, two helped it. Overall the PF moved from 101.6 (1966-69) to 98.7 (1971-74) across those 5 stadiums. Which is significant as there were only 12 teams in the NL at the time. Looking at those numbers you would expect the AB/HR rate to drop across the league by some amount. But we have already established it remains relatively constant. So there has to be some other variable that is driving AB/HR up at a rate that would make the overall numbers seem steady. Expansion teams and rule changes, LDO.
But that would only explain Aarons road AB/HR staying constant, not increasing. So I hypothesize that if you took the 3 new stadiums that depress offense as well as the new Fulton County Stadium out of the mix, you would see that AB/HR increased across the rest of the National League stadiums. So if Hank played 81 road games a year, 24 of those would be at "new" stadiums that depress runs (HR's), while the remaining 57 road games would be at stadiums that actually saw an increase in runs (HR's), leading to an overall uptick in AB/HR.
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