It is very difficult to answer a question like the one you ask without seeing the contract. The important issues to identify are as follows: (1) Is there any ability for you to terminate the agreement at will? You may suffer some financial penalty for the release. (2) Has the other party materially breached? This does not mean that there is a minor breach but something that goes more towards the heart of the deal.
Taking a look at what you wrote, if the team is supposed to consist of players her age but they do not have enough players and will fill in with younger players, that likely could be a material breach. However, you must look at the contract to see exactly what the school was to provide. If it was silent and ambiguous, this could work to your advantage since any ambiguity would likely be read to the disadvantage of the school that drafted the contract. As a former little leaguer myself, there is a tremendous difference in ability between grade and high school children. That is the area that seems most likely to promote the settlement of the matter you wish.
Regarding the values and teachings -- sounds like an afterthought and that didn't change from the time you signed the deal. You knew or should have known what you were getting prior and cannot complain later.
This may not be an open and shut case -- many will question whether your sending your daughter to this school was so heavily dependent upon the sports program. I don't know the facts and this could be a very important factor and be prepared to defend your position. Regardless, you may have some leverage in negotiation in telling them the school that the situation is clearly inadequate and unacceptable and they'd best settle because they cannot provide what was promised rather than deal with a lawsuit and the adverse publicity that could result. Good luck and let us know how you choose to handle things and how they work out.