Posted By:
jeff sbut i seem to recall that no one knows for sure.
one speculation i remember is that is has to do with people like Frank Chance who, when they got their hands on the ball, would put foreign substances on it, thus helping out the pitcher.
i also seem to recall that, in the old days, since the ball was harder to hit the darker it got (and balls were kept in play for a long time), when a new ball came out, players would do what they could to darken it up.
unfortunately, i have no clue where i read this stuff, and my library of such materials is 2,000 miles away...