QB/TE dilemma. Opinions welcomed

10 man .5 ppr

Team is…
QB dak / Mariota
RB gurley / fournette / Freeman / Perine
WR diggs / Bryant / Jeffrey / Corey Davis
TE Vernon Davis / Greg Olsen
D chargers / cinci

3 WR 2 RB and flex is the setup

Dak has been flakey, Mariota just as bad. On the waiver is keenum, tyrod, mccown. I’m okay dropping Mariota with what he’s looked like, opinions on best spot start?

Dropping Vernon Davis doesn’t bother me after he goosed me - options are Charles Clay, Doyle, Hunter Henry. Thoughts?

I’m swapping bengals D with Minnesota D.

Opinions? Or should I stash Vernon Davis or Mariota and just roster one D? The team has been flakey and landed me 5-7 even though it seems stacked.