Again, I don't know and can only guess. Ask Kovalev. The whole "actress" ordeal is strange and weird in many parts — I would rather not comment on it until we know more.
Probably was a bit lucky. If he was Wilder, who often bases his strategy on landing a huge right hand and gives away rounds in the meantime, maybe not luck. But since he isn't some KO specialist and was getting outboxed and even hurt, but turned the fight on one big shot, I'd say it's a bit lucky. I hope Kovalev wins, because it will prove that the KO of Jamie wasn't a fluke and also it will make her feel better about her loss, since it would demonstrate that Krusher still 'has it' and she wasn't destroyed by a shot fighter.
Kovalev is s 5 round fighter at this point and unless he improves his stamina Alvarez will take him into deep rounds and beat him again.