Contest Upate: Clue #4

This may take a little longer than I thought.  It seems as though the blogosphere may still be waking up on a Saturday morning!

I posted a question earlier this morning about my humble little collection: Who is the only other non-Cub, certified, on-card autograph of a Hall-of-Famer in my collection?

Here's what we already know:
1. Not a Cub... this is not very helpful, as that narrows it down to 29 other franchises.
2. He's in the Hall of Fame.
3. He was a hitter.

Here's the next hint for those of you out there participating:
4. He played an overwhelming majority of his career for a National League franchise.


Post your guesses in the comments section.  Again, you are limited to one guess on this post, and then you may guess again after the next clue is revealed, which will be about in another hour.