Short answer, no, you don't need a release. If you were selling a large enough volume of any given picture it might cross the line into "commercial use", for instance taking a picture of a single player and turning it into a mass-produced poster sold in retail stores. But outside of that you should be fine. The thing to keep in mind is that "selling for a profit" and "commercial use" are not the same thing from a legal standpoint.
Of course I'm no lawyer, but then again neither is Dan Heller. You might want to check out the
Photo Attorney blog or Bert Krages'
book to see what an actual lawyer says on some of these issues, the blog is very informative.