Let's keep it fun.
This came up in conversation while breaking bread with some fellow college football enthusiasts. Forgive us, but we are deployed and the OSU game doesn't start until 0430 Sunday morning, we are not "overlooking" the rest of our opponents with this discussion.
Scenario 1 - A 1-loss OSU team is Big Ten Champs, goes to the playoff and wins the National Championship in 2019, but the one loss is a big one to Michigan. (I know that is unlikely because that loss would most likely also cost the East, but it is still mathematically a possible scenario)
Scenario 2 - Undefeated OSU (including beating Michigan) wins the Big Ten but is either left out of the playoff and wins a Rose Bowl, or goes to the playoff and loses first round.