One of the single most difficult disciplines in "people" photography; the candid portrait. Technically, the images are all fine, good exposure, no extremes of light/shadow, or WB concerns, but as has been mentioned, they all have compositional issues. One of the things that separates a candid portrait from a snapshot is the way in which deals with composition.
#1 Looks like it could have been improved my aiming to camera right a little more, and perhaps from a slightly higher vantage point, shooting down onto the subject. This would probably have eliminated the "distractions" previously mentioned.
#2 I believe this one should have been shot from a wider perspective to situate the viewer better. As it sits, there's more action going on in the background, unrelated to the main subject than there is in the foreground. A broader perspective with a shallower DoF (to more effectively isolate the main subject and ideally one or two of his fellow players) would have helped.
#3 This is a really great capture, and, IMHO, avoids "excellent" only by virtue of the fact that there are unwanted people in the background. As per #2, a shallower DoF and moving the camera more to the right would have really helped.
All in all, nice work; you've got the technical fine, now it's time to work on the artistic.
Just my $00.02 worth - your milage may vary.
~John