Kovalev is slow, and so is Stevenson. As soon as a good slick fighter takes them on, they will lose badly. I'm thinking of Hopkins and Ward.
Watching Kovalev, he obviously hits alot harder than it looks. His punches dont seem to look fast or hard but they have massive affect when they land
When i saw his pad work in the dressing room before the fight i couldnt help but be like "damn". fast, powerful, and accurate.