Sam's apparent skill enables him to push the edge of professional sports' acceptance of homosexuals. If he was not a top draft pick and was instead a "maybe" or even a "probably" then his coming out could mean he had no draft prospect at all. What if, like Tebow, his professional skill is not a the level that people expect of him at this time? It seems to me that could result in a potential backlash against gay athletes.
That's a real risk. Sam is very much more in the "probable" camp than the sure thing camp. He isn't a first round draft pick given concerns about his size and flexibility, but he does project to be at least a good (or rotational) NFL player. The potential for a wash out is still there. 3rd round talents flame out every year.