I think you are joking, or maybe being sarcastic here?

“DNC chair is an administrative/organizational position, not head of policy,” so who cares who warms that seat?

I have no idea what you intended to say with “Obama preferred Perez, and when it comes to winning elections, Obama’s got nothing on Bernie Sanders.” I’d say a Black guy who gets elected to President twice in America has a pretty good skill-set when it comes to winning elections!