I say bigger. Eddie Chambers isn't really known as a puncher, at least Brewster had the punchers chance, so that KO wasn't totally out of left field.
I'd be shocked if it happened now. Wlad under Steward has learnt to fight smarter and minimise the possibilty that an opponent would be able to get to him like Brewster did.
Its easy to forget what a huge upset Brewster was in retrospect because of the other good work he got done, but at the time he was perceived to have zero chance at beating Klitschko, while Chambers is an accomplished, well regarded prospect.
It would be real surprise. Someone said everything is possible with Wlad chin... well, yes, but Chambers has no punch and with his size it will be difficult to get through Wlad jab. And even if he lands something meaningful, Wlad finally learned to control panic attacs he was getting when hit. The bottom line is that Peter couldn't keep Wlad down with his power and illegal punches, so why anyone thinks Chambers can do it?
Compared to his jab before, I would say it's more pawing. His fight with Iggy, it seemed like he didn't want to sit-down on anything for fear of being countered and his glass chin possibly shattering again.