At that time Kovalev was much the better boxer and I think that would be the difference. A lot of hype has been made about Kovalev's power but I think its his control of distance, jab, and timing that made him so dangerous. Stevenson would be a live underdog but the correct call would be Kovalev.
It was a massive disappointment that they never fought each other. This would have been a massive boost to their resumes and given fans the fight they were all eager to see. I think Kovalev would have won though.
I think Ward also kayos him tbh. He can stand up to Stevenson's left hand, and if he can grind down and stop a 33 year old Kov he can do the same to a 36 year old (start of WBC reign) Stevenson.
Kovalev was the better all-around fighter but Adonis had that great equalizer. Who knows how Kovalev would’ve handled being drilled by a couple of those. I would’ve made Kovalev a slight favorite.
Average jaw vs. supreme power; near-glass jaw vs. near-supreme power. If a betting man, I'm going with Kovalev every time.