I don't think Biden needs to be front and center. Trump being there is enough. This election is all about Trump to begin with, with CoronaVirus, it double down all about Trump.
Unless and until Team Biden have a well thought out plan to deal with CV19, and the other issues, it is best that they stay under the radar, especially given Team Trump's eagerness to deflect responsibility onto the Dems.
Far better the Dems figure out a solid attack plan AND ALSO a solid set of ideas to offer up, than just engaging in some stupid Twitter war.
Besides, Team Bernie IS putting out some solid ideas, might be a good time for the Dems to listen to them a bit more...yes, even Joe should listen.