I agree, the Tucker from today is worlds apart from the Tucker when he was drafted. However, he's still not there. He needs a couple of years seasoning in the AHL to help with his consistency and also (further) improve his skating, for example, to be able to become an NHL regular.
is there a chance on him becoming more then a bottom pairing guy? Sure, but he will need to keep on making big steps the next couple of years and while this is not impossible (we've seen it happen with other players), it's not probable.
PS. if he turns out into a bottom pairing-level player, that doesn't mean he will play on the bottom pair. Gunnarsson also wasn't a top 2 defender when he was paired with Petro.