It was hardly a fluke win for Sanders, it was looked pretty inevitable from the first bell, more a meteor strike than an earthquake. I suspect he just has Wlad's number. That combo of speed, power, height and aggression is always gonna be a real bastard even for the (much) improved Wlad. Could go either way though.
Wlad is smarter and more aware of his complete fragility so he'd fight different... but it only takes one good, quick left from Sanders and he'd be in trouble all over again... certainly an even money fight at best for Wlad
It's never a foregone conclusion with Wlad's chinny chin chin...but in a rematch he destroyed Brewster and in two fights he battered the dangerous Peter. Of course, Sanders presents problems with his "southpawedness", height, speed to go with his power than neither of the aforementioned did...but it still illustrates that Wlad knows how to survive and win if he perceives the opponent as a KO threat.
It shouldn't be understated how far both Brewster and Peter had fallen in terms of ability between their first and second fights with Wlad.