Doug Jones needs Roy Moore on the ballot to keep Bama from being an auto-loss.
It's really hard to knock out an incumbent from the Senate, but the incumbent hasn't held onto Tillis' seat in North Carolina since Jesse Helms' last reelection in 1996. Since then, it's flipped every time it has come up (02, 08, and 14).
Of the four dogfights you mentioned, the likelihood of flipping probably goes NC, IA, a large gap, GA, TX, and the rest. NC for the reasons I mentioned above. If the Senate is tied to the White House, Trump is under water by double digits in Iowa and Ernst hasn't done a thing to separate herself from him. There are also two more seasons of farmers getting trounced between now and then.
The large gap is there because Texas and Georgia are lottery tickets, along with the insurrection campaigns against Moscow Mitch and Leningrad Lindsey. However, if either of those two are sweating out a photo finish, the GOP has already lost control of the chamber and is having a bad night across the board.
The race where the presidential hopeful needs to get out and get into the Senate race isn't Colorado, it's Montana. Steve Bullock could single-handedly move this one from lost-cause to lottery ticket.