He did waste effort on headhunting against Agnew, but I suspect it was partly due to the KD2 leading Kovalev to believe Agnew was ready to be finished. Once he figured it wasn't gonna be that easy he started going to the body more and it became just a matter of time given that Agnews offense was virtually non-existent. What's most interesting to me is how Kovalev will cope with Hopkins constantly trying to interrupt his offensive rhythm - Bhops quick lunging right followed by a clinch has proved to be incredibly successful at keeping offensively minded opponents off balance. Kovalevs ability to adjust to this tactic is likely to be one of the most decisive questions in the fight IMO.
That's just one of several tactics Hopkins employs to disrupt a fighter's rhythm, and he often doesn't use his full arsenal in every fight, but tends to use similar bags of tricks against similar types of opponents. What's more important for Kovalev, I think, isn't the sneaky right lead, but the positioning. Hopkins is going to do his best to turn Kovalev, giving him unfavorable angles, keeping him off balance, maneuvering him out of position, and also to simply disrupt his rhythm. The footwork will be the key. If Kovalev has better feet and quicker hands than I suspect, Bernard could be in big trouble. But based on what I have seen thus far of Kovalev, I believe Hopkins clearly has the better feet and probably has noticeably faster hands, too. If that's the case, it could be a long night for Kovalev, even if he finds his range and distance, Hopkins may still have success turning him which can largely neutralize big parts of his arsenal.