He was catching the guy with long single punches jabs and lead rights. He isn't slow at all, he has good speed. Very patient aswell never out of the comfort zone, knocking people down with jabs ala kovalev style. Kovalev will need to box this guy from the outside because artur has ridiculously powerful short left hooks, stevenson will need to develop a few more tools before fighting beterbiev, but he won't so he gets starched. Ward has no business up at 175lbs. He would be a ko victim to all three of these beasts.
I disagree with the hand speed. I don't think he is a slouch, but I don't think he is that fast. I think his ability to catch Johnson was due to his ability to predict where he was going. A few times when johnson leaned out beterbeiv was throwing a punch while he was right in his face, but he knew johnson would lean back so he shot it in the space behind where his head currently was. He did other moves like this, I know all boxers do that to some extent, but I thought Beterbiev was doing it better than most in that fight. He does have good technique as well when throwing certain shots, which makes them seem quick. Overall I don't think he has that great of speed.
He's not nearly as slow as some make him out to be, but he sure isn't fast. He's got great timing though and has shown to be able to punch hard while his body isn't perfectly aligned. Also great in predicting his opponent's movement like already mentioned. Very good and dangerous fighter overall, who can stop just about anyone when hitting them cleanly.
:nod Also if his body doesn't need to be perfectly aligned to generate a punch worth defending, then that can replace speed. As he doesn't need to take as much time to set his feet.