Just for reference, 21 is average. This means a person who has average intelligence (IQ=100) would be most likely to score 21.
However, the test is really designed to test quick decision making, and wide receivers tend to score the lowest on this measure to begin with. Centers and quarterbacks--people who have to touch the ball on every play--score the highest.
Still, I don't think the correlation with football is necessarily that strong. Tony Romo dropped a 37 on the test, and his on-the-field decision making has at times been suspect. If I were a GM, I'd want to get everybody to take a Myers-Briggs test instead. That will tell you how they tend to prepare themselves and how much they hate losing--basically, Myers-Briggs tells you how your brain is wired.