At worse he's going to get Lay & Prayed to a boring ass loss. Ass-whooping? Usman won't put a mark on him. There's a difference between getting dominated and getting your ass whooped. Usman can win, he cannot whoop his ass though. I'd much rather get an "ass-whooping" from Usman than one from Mas. Did he even punch Woodly once? I mean he made him look like a baby for 5 rounds, but I don't remember him inflicting a single bit of damage. UFC hasn't seen Lay & Pray of Usman's ability since the days of Jon Fitch.
Usman has 11 fights in the UFC, with a whopping 1 KO, 1 TKO and 1 submission. No way in hell he'll be able to do any of those to Mas. Is wall and stall or lay and pray in your definition of ass-whooping? Those are the only 2 ways he wins.