Don't crop so tight.
You want to leave room on the print in front of the player, so he has "room" to run into. It looks odd when he is running into the edge of the print/image.
Good shots.
You have better lighting than I have at my local high school. I don't count on seeing the faces inside the helmets.
The more you shoot, the better you get.
Thanks. It's unfortunate but with a 400mm I can crop tighter if need be, but I can't crop looser, what is there is all there is. I haven't found a way to win at that game, sometime a 400 is too short, sometime it's too long. Same with a 300, same with a 600.