It's about 7 carries per game, which isn't a lot, but it's enough to keep defenses honest.
The thing about Frost's offense, is that you need the QB to WANT to run the ball at the appropriate time. With an RPO, it's great to have the threat of the pass and the RB run game, the 3rd aspect of that play is the QB run play. If you have a QB who doesn't WANT to run the ball, then it's going to hinder the offense. I am not saying POB or Gebbia doesn't have the ability to run the ball, but will they "want to run the ball". They were recruited to a system that would have them stand 7 yards behind the LOS and sling the ball around.