Look at it like this. Canelo has only looked like an A level fighter v. Rhodes, Matthew Hatton, Cintron(who was shot), Vasquez(who was a good deal smaller), and Angulo(who never had a belt and was beaten to pillar to post v. Kirkland). He was pedestrian most of the time vs. Trout and Lara and juvenile v. Floyd. B- fighter at best.
B+ fighter with A fighter upside. I label Guerrero, and Broner, and Maidana B fighters, and he's better than all of them
B+/A- Even fights with Trout and Lara prove he's a credible contender, but was clowned off the stage by the one A+ fighter he fought.
I'd rate him a solid B+/A- a loss to Mayweather isn't bad and 50/50 fights that he won vs fighters who were supossed to blow him out in Trout/Lara shows he has some skills to complete with his divisions best.
Seems an obvious B+ grade. Looked pedestrian against Trout and Lara, eh? How about he has beaten the #2 ranked JMW in Trout and Lara by the age of 23?