The question says it all; talking about athletes here. Is sunlight bouncing off one’s cheeks into one’s eyes that much of a problem? I can hardly even see my cheeks. Seems like the sunlight bouncing toward me from everything else is a much bigger problem.
I’m sure that it is highly dependent on the shape of the particular person’s face. I could see someone with deeply inset eyes, or very appley cheeks, benefiting. Others, like myself, not at all.
I have a very flat face and, even straining my eyes looking down, can’t see any cheek shadow in my periphery.
My nose, on the other hand, is quite the statuesque Roman beak, and any anti-nasal-glare products would be of great benefit to me. 
I’ve been wondering about this, since Brian Urlacher of the Bears always wears the stickers. I was wondering if they really help him see better, or if he wears them because they make him look meaner to the opposing offense! I’ll bet that’s part of the motivation in football. The difference in his appearance is pretty marked, IMO, when he has them on vs. when he doesn’t.
Well, sometime when sunblinded or snowblinded, just extending my index finger and thumb across the bridge of my nose under my eyes and over the checks will fix things right up for me, without obstructing any of my vision. It’s not the blocking of the light from below (often in my own shadow), but the far away light bouncing off my cheeks. I’ve always wanted to try that black goop in the winter, but didn’t want to look like a freak. You know, off the football field, that is.
it might be worthwhile to ask how much he gets paid to wear those little stickums on his cheek. I’m pretty sure that all the players get paid to wear those nose stickers.