I just did a quick pull of my sales stats by photo (thanks Exposure Manager) and found that the highest sellers are individual shots.
Although I can generalize that the best sellers are "individual action shots", turns out that the highest two sellers (by a large margin) are more like "individual sportraits." For example, the highest seller has been a shot of a little league catcher crouching in the rain behind the plate and watching the outfield in between batters. No action to speak of.
Anyways, being that I also shoot for the local newspaper, I have been able to notice that the photos that tell the story of the game (and thus run in the newspaper with the accompanying story) are not the shots that parents buy. Meanwhile, the photos that parents buy don't tell the story of the game and thus do not run in the paper.
It's almost like I have to shoot with two purposes in mind: images for the paper to tell the story and images that parents are likely to buy.
Geez, that was not a very direct answer, but I hope it helps.