In fairness, Schaub is a tough opponent for a lot of heavyweights. Yes he doesn't have the best chin but he is a very strong puncher with a good offensive striking. He's in my opinion a much better offensive striker than Gonzaga, and a rough match-up for Rothwell.
Gonzaga is a solid pick at these odds, especially with MMA the variables people use to calculate chance of success can vary so wildly that sometimes both sides make a ton of sense to bet on. I just really think Rothwells got this one in the bag.