Manafort was his campaign manager...
He handpicked the VP, but really he was a nobody lol. Good one.
I doubt Manafort "handpicked" Pence. Pence was a political winner because he could hold on to Trump's religious support practically no matter how many hos Trump has ever consorted with for a good price. Pence is a political moderate with a lot of appeal to the RINO republicans as well. If you could like Bush, you would love Pence. I mean that in the sense that he is personally decent. I know a lot of folks thought of Dub that same way.
If anything. Manafort was a strategist with some political sense, and I think Trump prefers sensible people whatever their character over ideological live wires like Bannon who just believe so passionately they can hardly take a minute off to go pee.