Zarate slows down Canizales' fast footwork with body punches and eventually wears him down to a late round stoppage. Just another level fighter compared to Canizales.
I think Canizales goes the distance. He was very good defensively and had an awesome chin. I think Zarate's length and artillery is too much for him, though. The strategy he showed vs Vazquez is almost certainly what he'd use here. His in and out movement, constant level changes and work in the pocket would likely make it a cagey battle in the early goings. Zarate would time him though, cut the ring off and really use his reach. In short, I think it'd be like the Davila fight, but it lasts the full fifteen. Zarate UD15.
I think Zarate gets Canizales out late. Not a clean stoppage, but the ref would be forced to step in and save Orlando. Probably circa 12-13.