We’re in a weird place right now where the national polls are looking better for Biden but the swing state polls are still looking pretty bad for him. However this looks to be the same polling outfit that showed close races in the rust belt trio.
I’m not skilled enough to offer a thorough explanation for this, but I still feel better about Biden’s chances compared to a few months ago.
I don't think the national polls are looking that great for Biden? It generally averages to Trump by less than +1. Biden does have a few +1 or +2 leads out there, but that's not really consistent with the median state in the EC being all that competitive. If 2020 was Biden +2, he probably gains nothing over Clinton 2016 in the EC except maybe Michigan. If you assume Trump is getting an additional 1-2% out of NYC and Florida, maybe that nets Biden Pennsylvania and Michigan while Trump wins all his other 2016 states (and with the clear Hispanic R trend, NV). That's basically what current state polling looks like. Biden might be up in PA and/or MI but he's in huge trouble everywhere else, and state level polling in WI understates Trump like nobody's business.