They look good to me.
The second one could do with a much tighter crop, and the third one, while a key action moment, suffers from having no faces and having to have the photographer point out where the ball is. To me, images that show fumbles and suchlike should have the fumble as the blatant central point, rather than obscured by players. Tough break to what was capturing a key point in a 'game' (even if it was just a scrimmage). 
Edit - Was your overhead light consistent across the period of the scrimmage? If so, you should consider making a meter-reading and set your exposure manually. With the very bright backgrounds, your subjects are slightly underexposed in the foreground, as you already mentioned. A cheap light-meter CAN make a world of difference, but if your light fluctuates second-by-second it can be a hindrance. It's a judgement call on when to use/not to use it.