I wouldn't be suprised to learn that players back in the day took roids as well... and my suspicioun grew a bit bigger when some guy (I forget who) was quick to defend Bonds when asked about his record chase and what he thinks about it if Bonds were indeed on steroids.
The only "proof" I (and anyone else) have of Bonds being on roids is the drastic increace in numbers from 1999 on, which coincided with the point of his career at which most everyone else starts declining.
I admit it's all speculative, though. Some people aren't even willing to admit there's a possibility, however, which is pretty closed minded and (in the majority of these cases) homerific.