I know this was at least in part a gesture of modesty on Biden’s part, but it’s also correct and I hope he ignores the media and applies it in practice:
Many political scientists also say the data doesn’t show the vice presidential pick affects the outcome of the race much, anyway. Biden himself even made that argument during the 2008 general election, telling supporters in Ohio that “no one decides who they’re going to vote for based on the vice president.”
“I mean that literally,” he added.
There’s a line of argument that goes “even if VP selection is normally irrelevant, maybe the pandemic and the candidate being 78 will mean it matters more to voters this time.” Even assuming arguendo that this is true (which, with Donald Trump the incumbent on the ballot, I don’t actually think), there’s absolutely no empirical basis to determine HOW it would matter or how any individual pick would impact the race. It’s all just a bunch of purely speculative just-so stories: pick someone who will mobilize the base, pick someone to reassure Trump-averse educated moderates — nobody knows. The VP will probably be immaterial and even if it theoretically could be material it’s inherently impossible to determine such an impact ex ante.
No need to overthink this. The pick should be a progressive woman, based on whether they would be good at presidenting and vice presidenting. No purple or red state senators, no baggage like a history of throwing objects at staffers. Warren and Harris seem like the most obvious choices, but anyone who meets these criteria is fine. Don’t worry about anything else.