it's been said before that one of the hardest things for an untrained individual to do in any sport is hit a 98mph fastball.
i would tend to disagree, because i don't think anybody could ever come close to pole vaulting several meters in the air without extensive training and practice, but hitting a fastball is definitely up there..
regardless, you don't have to be in the best of shape to be a good ball player, but it certainly helps. roy halladay is probably the best pitcher in baseball and has been for some time, and he's a 6'6 monster whose strong as fuck, lean, and in his spare time plays sudoku and little mind games to help him focus and keep his mind sharp. that's the definition of an athlete right there.
oh, and to everybody arguing about which sport demands more "athleticism" and shit, read the title of the thread. there's no comparison in there. it doesn't say "proof that baseball players are the BETTER athletes" it's simply saying that they are true athletes (even if it were just as a joke). and lots of baseball players are true athletes. you have your occasional fat ass who gets paid to smash the ball a mile, but for the most part these guys can run like the wind, are jacked as fuck, play the game EVERY DAY OF THE WEEK and still manage to stay sharp, healthy, study the opposing players, etc.