OSU got their ass handed to them by Iowa last year, and by a bigger margin. Then they went on to beat #13 Michigan State, #3 Wisconsin, and #8 USC.
Having 1 loss doesn't mean they won't make the playoffs. Especially if they win the rest of their games and the conference championship. Even if Alabama, Clemson and Notre Dame finish their season undefeated, there will still be a 4th spot. LSU and Michigan will both have 2 losses in that situation. Ohio State would likely get the nod over Texas or Oklahoma (if they stay with 1 loss).