Interesting question, I think he is very sound (based on what we have seen of him). However how much is the competition a factor, and great reflexes/synapse. Has he fought someone who can take him out of his game, or neutralize his attributes. If he wins vs JMM which he should, how much will be attributed to being: being bigger, faster, more in his prime. To me when I think technical I think Sanchez or Duran, where speed isn't as much an issue. In a way I contradicted myself maybe.
Left hook/right hand leads Retreating in straight lines Boxes defencively on the ropes Ducks into his man without throwing a punch Wears his left hand low when being attacked Feints and then throws the punch he feints with Walkaway without a covering punch Retreats in straight lines These are some of his numerous technical sins. He gets away with them - often their absolutley the righ thing to do because of - his physical gifts, but still not sound.
One of the finest technicians there has ever been. No doubt about that; his skills are top-notch, even to ATG-standards. He can fight aggressively, box off the backfoot, mix those up, hooks, uppercuts, jabbing, right hand leads, adaptation, etc. A very complete boxer skill-wise. His sick speed did help of course.
In some areas he's technically sound. But he wouldn't be what he is if he ticked all the boxes with flaws that McGrain put forward. Some fighters are more technically sound but nowhere near as effective or successful. He's got on awkward style, a hard defense to penetrate, and he's sneaky and accurate with his offense. He's unbeaten so far in his career. Not bad going. Most unorthdox fighters aren't technically sound anyway. But being unorthodox works for them.
All this has served him well. Hard to knock it as much as it is not to ignore it. I wouldn't actually say boxing defensively on the ropes is a technical flaw as such. Left hand low, maybe so, but his shoulder is usually up with his right hand tucked into his chin to guard oncoming hooks. Again, hard to knock it when his defense is rather solid.
Floyd Senior may look like the host of "Tales from the Crypt" but he understands fundamentals. Floyd Jr. was doing drills since the age of 3. And it shows. Floyd is technically sound enough to innovate. His high level of athleticism is grounded in fundamentals and he can go at any range, has well-developed defensive skills, can counter, move well, and throws shots very well. He has at least B level technique -no, not comparable to Duran or Sanchez or Chavez but good. It seems superior because of the complement of speed and reflexes... similarly, other athletes are regularly confused with technicians because they punch fast and don't get hit because they jump out of range.
As I said in that very post, "often they're the right thing to do". Technically correct and correct are not the same thing, for sure.