I like Ragnar's post... never thought of it that way.
Walter has done some enormous things in bowling, and is definitely the best of our time. My vote for all-time, however, has to still go with Earl. He not only has the titles, he did it in a shorter amount of time. And if I remember correctly, he would take time away from the tour, come back, and win again. Then he quit until it came time for the Senior Tour, and while he wasn't a full-time player on the Senior Tour, he was still a winning force to be reckoned with.
Also, as I have been told, he would routinely be on the telecast during weeks when other lefties weren't even on the radar screen.