If you're looking for rules on this contest you can find them here. Good luck!
I'm not saying it will be easy, but I'm pretty sure you can theoretically nail this player down after this clue. A co-worker of mine was able to successfully guess this player after I gave him this fourth clue... though it did take him an hour plus the use of some of our internal tools, so I won't blame you all if no one gets it still. :D
Clue #4: Not that many people would care, but I've had a positive WAR in every season I've played professional baseball. That's not something Albert Pujols can say this year!