Would Fail: John Cena

John Cena is, obviously, in tremendous physical condition. His cardio and strength would not be in question in an MMA ring.
However, he has no real life combat sports experience. None! He played football in college and worked as a bodybuilder before transitioning to wrestling.
While John Cena in the UFC would no doubt sell a lot of pay per view buys and tickets, it's hard to imagine him doing very well with no practical fighting experience. Also,at a billed weight of 251 pounds (he's actually closer to 235-240) he's a bit undersized for the heavyweight division, but would have trouble cutting weight to be a light heavyweight. On the cusp competitors have done well--like Cain Valasquez--but that is due to their skills and experience in combat sports Without such experience, Cena would likely struggle against even an MMA novice. His legacy as one of the all time greats in wrestling is secure, but Cena should remain outside the MMA cage as a spectator.
Five wrestlers who would do well in MMA, and five who should stick to the sidelines.
A top professional wrestler opened up on Goldberg HERE