I think you have that backwards. Kovalev is the worst possible opponent for Ward. The clinching, grabbing, and head butting won't work against Kovalev.
Kovalev is far too powerful and big for Ward, not to mention he's one of the P4P toughest punchers in the sport... While Ward is known for being feather fisted in HIS OWN division... It's risky business for Ward.. But hey, this has gotta be the most spectacular match up in over a decade. If Ward loses to Kovalev he shouldn't even bother staying in LHW, Beterbiev is coming!!
If I were Ward I wouldn't be afraid of Beterbiev... At least not nearly as much as Kovalev. I think Kovalev is the much better fighter. I however do think that Kovalev's power is what will win him the fight. Many of his opposition could have been beaten if his power wasn't A+. This is a fight where he will need to hurt Ward on multiple occasions or KO him to win.