The entire DNC convention was basically set up to tout Biden as a good decent fellow to mainstream voters, while frantically virtue signaling to lefties, and with the polls tightening, the lack of a convention bounce is bad news. You know it’s bad news because the media is frantically explaining why no bounce should be anticipated, and why convention bounces are a thing of the past, accompanied by other ‘This is Fine” explainers.
The Biden campaign is suffering from a structural problem. And the structural problem is that Biden summons little support on his own. His backing is largely anti-Trump. So a convention bounce isn’t coming. Why would it when there’s no real candidate and nobody, except Bernie supporters, really cares who’s on the ticket.
All the warmed over Obama stuff doesn’t work for Biden. And Biden tends to poll better when he’s out of sight.
The Democrats have actually reversed the law of political gravity with a candidate who performs best when no one sees or hears him, leading to the possibility of a convention drop, rather than a bounce.