Here's what I suspect...

It was reported that Bryce Drew turned down the initial DePaul offer. I don't think it was money, so what else? Well, Marcus LoVett is on campus this weekend. Billy Garrett Sr is handling his recruitment.

Supposedly DePaul feels they have a lot at stake with LoVett. If Drew wanted all his own assistants, DePaul might lose not only Garrett Sr, but Garrett Jr and LoVett.

So instead, they hire Leitao, who they already know on past history will put up with their crap, he keeps Garrett, they keep their roster and prized recruit (not that LoVett is much of a prize).

That's my guess.