The arm bar is not the problem. It was the fact that she was leading with her elbow instead of her forearm. She was driving her elbow into Teaira's lower back all afternoon, and that's very poor reffing. That's how players get injured.Post defenders may use an arm bar against an offensive player whose back is to the basket, with or without the ball, but the forearm may not be extended to push.
NCAA rules change — confusing coaches, players and fans alike