Even though I am as high on Conner as they come unlike others that have posted above me, I would still trade Conner for Mixon today if it was offered to me.
There's four Conner/Bell scenarios in my opinion:
1. Bell comes back next week and takes over the starting job completely.
Not likely at all in my opinion.
Mixon >> Conner
2. Bell comes back week 11 and takes over the starting job completely.
Also not likely at all in my opinion.
Mixon > Conner.
3. Bell comes back week 11 and splits carries with Conner.
A decent chance of happening.
Mixon = Conner
4. Bell comes back week 11, but doesn't play but a handful of snaps at best the rest of the year.
Most likely scenario in my opinion.
Conner > Mixon