Tulsi Gabbard felt the need to resign due to her support of Bernie Sanders. That tells all one needs to know about the Vice Chair being a fluff position. Ellison is there to try and fool progressives.
Screwing Bernie, then picking Kaine, then going for Perez tells the story of what the DNC establishment really thinks about it's everyday supporters.
Those people want candidates who are not beholden to large donor and lobbyist interests. Democrats serve up exactly that. But try to rail on common decency social issues as a way of fooling people into believing they are not Republican lites.