#1 - OK, but I'd like to see the player's eyes. Sometime you only get a brief chance to catch the eyes, so you gotta be quick (which I know you are).
#2 - Nice shot, but should be vertical FWIW, when I shoot soccer on a full-sized pitch with a 400, I am vertical almost the whole time, other than when the action is way on the other side of the pitch.
#3 - Good action (the white balance seems off on these, BTW), but cropped a little tight.
#4 - I like it, but it would be better if the player is JUST letting the ball go. The ball is blurred, too - what was your shutter speed? Another BTW: include your EXIF info when you're looking for C&C: most people, like me, are way too busy to go to your Flickr account to get this info.
#5 - Good facial expressions - but the shot is really crowded. This is why it's tough to get action at midfield sometimes - there's a lot of players!
#6 - Nice, but again, no eyes. This might be tough, as by the time she looked up, chances are the ball would be out of frame.