As some of you are aware by now, the School of Friendship is like Hogwarts. It's like the Xavier Institute for Gifted Youngsters (aka the Jean Grey Institute for Higher Leaning). The mutant school has basketball. The wizard school has Quidditch. And the School of Friendship has Buckball. However, despite her deep knowledge of the game, Rainbow Dash wasn't chosen to teach Buckball at the School of Friendship! Who did they choose to teach Buckball? And how will Rainbow Dash react to not being chosen for this particular teaching position?
This strikes me as yet another example of "Rainbow Dash is wrong only because the episode says she's wrong". There are other Ponies more qualified to train the cheerleading squad, and putting Rainbow Dash in charge isn't fair to those Ponies. And we have Rainbow Dash doing a job she's not qualified or trained to do. Twilight Sparkle should have assigned the job to someone actually qualified to do it, but the episode never calls Twilight on it.
This was a misallocation of resources to prove a point episode. RD should have trained the athletes. There is a misconception that being good at something means you are also good at teaching/coaching it. This is usually not the case. RD trained the champion team, why wouldn't you have her train the new team too?
This is exactly my beef with the episode. Rainbow Dash is only wrong just because the writers said so, otherwise she's entirely on the right.