Teams change throughout the season, especially at the college level. I think most experts would agree that Hio State is a bettter team than they were at game 2 this year. Most experts would agree that Oklahoma was a better team at the end of last season than they were after the loss to Ohio State.
The second issue is because of the limited playoff spots, once a team loses, their access to the playoffs depends on what other teams do.
Finally, the process of the playoff committee isn't designed to determine who is the best team at the beginning of the season and whether they can hold on to that spot. That was the old ranking system. The process is designed to find the best team at the end of the season. Let it play out. OU is in good shape where they stand.