For comparison purposes, the Massey Ratings, a college football composite of 55 ranking systems plus the AP and USA polls, currently has Alabama #1, Oklahoma #2, Clemson #3 and Ohio State #4.
http://www.masseyratings.com/cf/compare.htm
To round out the top 10, Michigan State #5, Iowa #6, Notre Dame #7, Stanford #8, Baylor #9 and Florida State #10.
The current S&P+ ratings also have the Buckeyes at #4 after last week's game. So, given play through the regular season, Ohio State is in the top 4, according to a widely-cited composite ranking of every rating system out there, the Massey. But not playing in the conference championship game hurts the chance to retain the #4 spot.