You do have a point. The tricky part while appraising Hagler is that while he struggled against several large, crafty MW in the first half of his career, he also ended up mangling him in rematches, proving how much better he had become. He was still a green, local champion before he went fighting ranked contenders in Philly.
There's no question that B-Hop schools a fresh out of Brockton version of Hagler. I also think old Hopkins decisions a past of prime Hagler, as his style is better suited to the later years. As for the early 80s version of Hagler, with the volume, agression and footwork, that may be a different story. Gun to my head, I still say Hopkins, as he never screwed up from a tactical standpoint, which Hagler could do. But this side of RJJ B-Hop never fought a MW beast like prime Hagler.