Purely my opinion, since I don't shoot many sports (and don't market them):
Chalk me up as another vote that if a vignette is added it should be subtle. There are a number of reasons I feel this way.
- A heavy handed vignette such as you've shown in these three image doesn't just steer the eye to the center of the shot, it frames and confines the subject(s). People viewing a sports shot just instinctively feel that this is wrong. We all know that the court or field is much larger than the portion captured in the shot so our guts just expect the action to be able to continue out of frame, not run into this dark wall of a vignette.
- If you are only marketing these to the parents of the subjects, you can call them environmental portraits if you'd like and probably find people more accepting of the heavy vignette. However, that limits you to marketing each shot to basically the parents of the one or two main subjects in the shot. Remove, or drastically reduce, the vignette and these become shots which could additionally be marketed as photo coverage of the game, or even as stock photography.
- Again, just my opinion, but a heavy vignette is too often a crutch. If the shot were done properly it wouldn't need a heavy vignette to pull the eye to the center. Yes, I understand that with sports photography things are so quick to change that it's difficult to nail composition, exposure, depth of focus, and timing to capture the best action. But honestly I think you've timed each of these shots just about perfectly - I'm drawn to the compelling action captured in each and really don't need the vignette to draw me to it.