I'll pick DC to win again. DC has proven that he has a iron-chin and can take Johnson punch as evident in their first fight. Cormier should be able to mix in his strikes, clinch, and takedowns enough to grind it out again, enough to take advantage either standing or with takedowns. Plus Rumble is not known for conditioning and will easily gas it out similar to their first fight. DC by decision.
Cormier will dominate johnson for the second time. Cormier has great strength than johnson based on their previous match, i think this rematch is just for good fight show. I hope that UFC develops some new fighter that can dominate current champions.
