The 'oldest' player I can think of, besides Lou Gehrig
, who had gone down w/ an injury really quickly would be Sandy Koufax, who also astounded everyone by taking time off for religious reasons.
I'm thinking and thinking and maybe it's b/c my 1973 HOF guide that I got when I visited there as a kid only had HOF'ers in it who played for long ass times, but I can't think of that many 'old timers' (not to really say that Sandy K was an 'old timer' although I guess he'd qualify now...) who were good but hurt, like say Schmidt or Prior. Maybe the guys who got hurt just...disappeared??
A lot of it too is the fact that they can just hop in the clubhouse and get an xray/ MRI and see what's messed up. Medicine is A LOT different now!!