As it stood, the football team had a good wide receiver in Steve Farber, he was fast, tall and had long arms to make catches. He also had that cocky confidence that really helped a team win. It was exactly what the girls Volleyball team needed, but none of the girls hit that profile, no one was gifted enough to be as good as Steve, had he been born a girl would be at that role. So the stone subbed in Stacy Faber for Steve, and then replaced his role on the team with some nobody girl who wasn't going to be good at sports anyway in Athena, making her Apollo, the star WR of the football team now. Both teams got upgrades.
At first Apollo was in a panic, trying to find a spell to turn herself back, but then Biff made the wish to make this all normal, and Apollo got back to doing what he did best, chicks and winning, it all came so naturally to him that it just was who he was.
Stacey Farber on the other hand was a very different girl than she was a guy, she was naturally talented at Volleyball, she had a killer instinct for the spike, but she was a tall bean pole of a girl, so she didn't have the confidence of Steve. In many ways she liked being on the court so much because it was the one place she felt "normal", where who she was could shine. As she got ready for school she knew the hallways awaited, where she would stand out, and she always felt like something of a freak, too tall to be pretty.