Choice No. 2 - Nick Mullens
Why He Should Start
Nick Mullens's best case to be the starter is that he may be the only quarterback on the roster who can run the offense most similar to Kirk Cousins.
Mullens can take off and run if need be, but he isn't the athlete that Josh Dobbs or Jaren Hall are. He's much more comfortable sitting in the pocket, going through his progressions, and finding the open man. If Kevin O'Connell wants this type of quarterback, then Mullens makes the most sense.
Mullens also has been in O'Connell's system for two years and is well-versed in it. He's unlikely to make the poor reads and decisions that Dobbs does and may be deemed the safer option as far as turnovers go.
While he may not put up big numbers, he could be viewed as a game manager who can make enough throws. With Minnesota in the thick of the playoff race and getting Justin Jefferson back, having a safe, game-managing type of quarterback to pair with Brian Flores's attacking style of defense isn't a bad thing.
Why He Shouldn't Start
Mullins is a backup for a reason. O'Connell could have turned to him during the loss to the Bears in Week 12, but he opted not to. He may be safer with the football than Dobbs, but he also has 23 career interceptions under his belt, so there's no guarantee he won't make as many mistakes.
Mullens also isn't going to provide those splash plays. Both Dobbs and Hall can make plays with their legs, and that dynamic would be lost with Mullens under center.
He also hasn't worked in any game situations with Minnesota's first-team offense, so there could be some timing kinks for a game or two, and that is a time frame the Vikings can't work with at this juncture.