What Pollard said was, "The last three years in the Big 12, the team that rushes for more yards wins 80% of the games." So, in conference games, if you out-rush your opponent you will win 80% of the time.
I do think a little context is important, in that teams like Baylor and TCU who make a living on big pass plays end up with a lot of rushing yards because they tend to build big leads over non-elite teams, and then they spend a significant part of the 2nd half running while the opponent has to pass to try and dig out of the hole. That's not to take away from the athletes and schemes of Baylor, TCU, OU and OSU, but forcing your opponent to throw either because they can't run or don't have time to run is a factor. That said, if you ARE taking away the running game and building big leads, you're doing a lot of other things well too.