One thing with Oleinik that should be a concern I guess is although he choked them out, Albino and Pesta took him down and got to half guard and full mount respectively.
Granted he was setting up the chokes so didn't fight the takedowns/guard passes too much but it doesn't really inspire any confidence that he'll be able to stop Werdum taking him down or passing guard whenever he wants if he does take him down and if he wasawas to have anycany of submitting Werdum, it's not going to come off his back from half guard or worse.
I can't remember much of the Volkov fight but prior to hat Werdum also built a very respectable striking game through muay Thai.
He may have regressed massively but outside of power (which definitely factors in at HW), Werdum should hold a big advantage everywhere.
I think this is a tune up fight for Werdum. He's a fairly big name and is coming back from suspension - he's never necessarily been a front runner himself in terms of quick finishes, he's willing to fight slow and has gone to a decision 1/3 of the time with a lot of the finishes coming later in fights.
My main concern would be Oleinik not having enough in him to go deep in a fight and I think it'll depend on his mentality. He could come out thinking he had a round to finish it and go out on his shield in round 1 with that kill or be killed mentality.
Alternatively, if he obliges we could see Werdum set the pace, rack up cage time and shake off some ring rust with a slow paced fight he clearly controls with a finish potentially on the cards in R2/3.
I'll check the odds later or tomorrow but maybe gut have something on Werdum Dec, his R2/3 props and maybe the over 1.5 or fight starts round 2.