What is forward progress?

[bansheexyz]

This is normally called when a player is stood up by a crowd of other players so that he can't naturally fall down. UCLA receiver fighting for yards gets knocked back 3 yards, tries to spin away from a SOLO tackle and is in the process of going to the ground when he fumbles the ball. Never heard a whistle because why, he's being tackled. Clear recovery by Iowa. But no, ref comes in and just spots the ball real quick. Like what? Never seen that brought back in my life.