Were you trying to be artsy or actually shoot the game? The vignetting is a little iffy if you are trying to get action shots. The action wasnt totally stopped in the pictures, but your shutter speed wasnt slow enough to give you a good motion blur, you are kind of caught somewhere in the middle. With the vignetting, it almost has a claustrophobic kind of feel, like the black is taking over, and makes the pictures a little bit too dark. If you look at the one picture without it, you can see that it is much brighter and vibrant.
Sorry for being so critical, on a lighter note, they are all pretty damn sharp, which lens did you use? Nifty two-fifty?