I may be way off on this, but the fact that you said she is "strong willed and that may be part of the problem" tells me there may be an attitude issue. Her talents are irrelevant if her attitude is one that the coach doesn't want others emulating. There are most certainly coaches out there who are just jerks and want to lose by playing "lesser" talent....but there are likely many more teenage girls who can be a bit unpleasant in the dugout or on the field.