Compare how Biden is doing to Democratic House candidates in each of these states. If Biden were a weaker candidate than average, these Democrats should, on the whole, be outrunning Biden.
The opposite happened: Biden is outrunning the House Democrats in all these pivotal states.
More to the point, Republican candidates for the House are actually getting more votes than their Democratic counterparts in all these states. As of this writing, the margin is less than 10,000 in Arizona, while it’s over 90,000 in Georgia, Pennsylvania and Wisconsin.
(Note: Democrats and Republicans had a candidate on the ballot for each House race in these states.)
In other words, it seems quite conceivable that the baseline Democrat may not have actually won the states that he or she would have needed to win the Electoral College.