His top wins are Weidman and Bisping and he looked meh at best against Branch. Luke Rocksalt was getting lit up on the feet until Branch decided for some reason to take the fight to the ground (Lukes strongest area).
Bisping is on a 2 fight skid and arguably 3 if you thought 46 y/o Hendo won the rematch, and Weidman just got his first win in 4 fights against a Welterweight.
Rockhold has some of the worst boxing in MMA and will be facing arguably the best boxer in all of MMA. Rockhold also has next to no take-down offense and Whittaker has the highest Take-Down defense % in the MW division and one of the highest in MMA.
I expect the Whittaker fight to be an absolute blow-out, Rockhold will last 2 rounds at best before Bobby Knuckles gets the KO/TKO.