If someone played, for example, from 1895 to 1907, his 1900+ seasons are eligible, but his 1899 and back seasons are ineligible.
While I am thinking about it, there is a rule that says, DO NOT MENTION ANY PLAYER BEFORE THEY HAVE BEEN DRAFTED. In basketball draft leagues we usually have a separate thread for rosters and commentary. In that thread you can talk about players who have already been drafted. You can say thing like, "hey chewy, getting Roy Hobbs in the 7th round was a steal,' or "Midge, you're an idiot, do you even know what a baseball is?"