Palmeiro had an average of 2 more hits per year in 163 fewer at bats, which is why he was a .300 hitter through those years vs. Bonds' .286.
But in Bond's 581 extra plate appearances, he had 437 more walks, of which 134 were intentional. Despite that, not only did Bonds have 327 more total bases, including 98 more home runs, but also 158 more runs batted in. Had he been walked as little as Palmeiro, the gap would have been that much wider, as the overwhelming bulk of those times there were men on base.
The stolen bases also set Bonds apart from Palmeiro. And, for good or ill, that one admitted to having done steroids though never having failed a test, while the other denied (and denies) it despite having failed a test.
You asked when I thought Palmeiro might have started and I would guess the same year that Bonds did. Palmeiro hit .254 in 1997 and bounced back with .296 in '98, then .324 in '99. Perhaps in May of that year, when he realized he could not catch up to the ball, hitting .239, followed by months of .354 and .326.
That's all guesswork. I could just believe him that he never knowingly took them and that it was coincedence that after a declining batting average for 5 years after that .324 he bounced back in 2005. But he slumped out of the gate, hitting .247, before rebounding with .302 in May.
He did not recover after the suspension and never played again after the end of August 2005, despite asserting that he could still hit. "It's all in the mind," he explained. But it wasn't - it was all in the body.
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