Brow, Shaq, Yao, KG, Hakeem, Amare, Dwight, Robinson etc etc etc all helped turn their teams around within 1-3 years of getting there.
I could also point out some guys who posted gaudy numbers, but couldn't lead their teams anywhere, Al Jefferson had a 23/11/2/2/1 season a few years ago
Lets not act like they were 28-8 when he went out, they were 9-6, that is basically the best 15 game stretch in his entire career as far as defense is concerned.
It's never Cousins fault, please explain to me how it's not a centers fault when his team is losing when we know for a fact they impact the game more than any other position. Look at the damn Utah Jazz, in only his second season Rudy Gobert has been the main driving force behind their current surge of wins. We saw how that team looked without him starting, and they're 15-8 with him in the lineup, you can see Anthony Davis impact as well, great big men make an impact on wins and losses.
You missed the point, Vucevic is a good center, but he's not a franchise player and he absolutely needs defensive players around him to make up for his own lack of it. Cousins is in the same exact boat, he just gets a lot more touches on offense and these gaudy numbers don't lead to wins, his usage rate is retarded.