maralieus
Lets get those balls deep!!
I never thought of that, but I think the second part of your post shows part of the reason the roof should hold. With air moving under it about as fast as it moves above it, there would be no Bernouli effect to lift with a low pressure. Even the part above the field, inside the stadium is really outside, but I guess the air inside the stadium would not be moving as much. Still, that's a small part of the whole canopy so I think it should be fine, especially with the supports underneath holding it down (and up).
I'd rather have shade than a warm breeze though. Do you think the field would be hotter with the additions? Because that would be a great thing!