The thing for me that made the difference was the experience and better skills of Marquez. Yes he got mobbed Diaz as he came on strong in a big way in the first couple of rounds but it was clear (to me) that Marquez was looking to select his shots rather than just survive or charge in like Diaz.
He weathered the storm and got to work at distance. I think by round 4 we could see how this was beginning to play out. The only doubt was going to be who tired most first.

Very good performance by Marquez.