I think they switched the single due to the good reception "Boy Outta Here" received from inside the industry. Not because anything "flopped".... Sweat was never released or pushed.
Boy Outta Here will definitely not be a generic dance-pop song, since it features Rick Ross, so that's good news! I hope it's good. If so, I think it could be a big hit.
someone said the pictures of her goin into a dance studio with Jamaica (her choreographer), they were actually doing a test shoot for "Boy Outta Here" with Codie (the dancer) from twitter helping with assisting the choreography. So my guess is that they ways had the intent of releasing "Boy Outta Here" as a single but they probably threw "Sweat" out there to see how the response would be.