Perez knows DNC has to earn progressive votes

And said as much. DNC Chair Perez is meeting with Jeff Weaver of the 2016 Bernie campaign to see how they can coordinate concessions to Bernie's agenda. Note that to date the Biden campaign has already conceded lowering the Medicare eligibility age and forgiving college student debt for low-income families. Perhaps this will reassure at least some of the Bernie supporters that Bernie's agenda will at least be partially implemented. Which, by the way, is a LOT more than we're going to get from Dump or the Repugs, meaning nothing. Ask yourself if you want something or nothing. Or likely worse, total fascism.