I certainly think that baseball is a fantastic grounding for keepers. Im only 5 foot 5 but come from a gymnastics/trampolining background and that has helped over come my height problem. But, when I play and sport involving the batting of a ball, ie baseball, cricket etc, I usually find I pick it up easily.
Tim Howard is actually a very good technical keeper that many people miss. That he has had to pick up along the way and will not come from any other sport. He (despite what others say) commands his box better than most keepers, communicates very well with his defence and on top of that his positioning is spot on. Its very easy to blame a keeper for not communicating, and always happens when there is a mix up. Commentators always say there was no shout from the keeper. Defenders often ignore a shout and thats where the mix ups happen. Just looks bad on the keeper and have seen Timmy accused of lack of communication time and time again.