I fully expect that a new hitting coach won't change anything with Vlad. A LOT of pro athletes don't want some 'coach' telling them what to do. Most don't want to hear the truth on why they are failing. And to some extent, I get that - especially if the current hitting coach tells him one thing and the new hitting coach tells him something different (obviously it would help if multiple coaches tell him the same thing).
Instead, Vlad will probably listen to what his Uncle - or some other trusted family member tells him over any Blue Jays employee. He'll 'think' that it was his Uncle that got him scouted and "to the majors" and thus he knows best. And because he's Vlad, the Jays will probably give in and fly his uncle in - just to tell Vlad what he wants to hear. A lot of the pro athletes surround themselves with yes men.
Now I must admit that I didn't come up with most of this; however, I was speaking with one of the Leaf's technical coaches and that's essentially what he told me. He said there are several Leafs who refuse to even work with him because their ego is too big. But Cousin Bill who knows next to nothing about hockey gets flown in to tell them what they want to hear and make them feel good. I fully expect this extends into baseball and all professional sports.
The Jays need to find the right person to deliver the message to Vlad - you're too out of shape - dedicate yourself to the game if you want to be a star - take your walks and stop expanding the zone so much - etc.