So bring in another QB even though he stinks just to have 3 or 4 contenders to start?
Yes, I prefer Tuel to McCown. There may be a 1 in 100 chance that Tuel will become a solid starter but that's better than McCown. At this point in his career McCowns is what he is.
Mike Ditka used to say that your goal should be to have only two types of players on your team: Players that you can win a championship with and players who you believe can become guys that you can win a championship with.
Which one is McCown. If he's neither, then what's the point of bringing him in?