The red wave came up against the winds of mail ballots.
First a note to those who might be newly engaged in politics or have forgotten: It isn’t at all unusually for the media narrative to switch after the votes are in. Thus, whereas before, commentators would say that it might be such a big “red wave” that the Republicans would take the Senate, indicating that there could be a wave even if that did not happen, afterwards, that switches to insisting that there was no wave at all because the Republicans didn’t win the Senate by several seats (or, at this point, might not win it at all).
That said, declarations that the red wave did not emerge, compared with other midterm elections are tending to ignore that this is the first midterm in the new world of post-COVID mail balloting. In economic terms, mail balloting moved the supply of ballots down and to the right, meaning that more could be had for a lower price, and given their constituencies and organizational structure, Democrats benefit more from that.
That’s part of the current political reality, and Republicans have to solve the puzzle.