Yes, Tyrod has had sub 100 yard passing games in two instances: NO (who was in his face all game long) and NE game 1 (where Tyrod got his knee tweaked in the first quarter), so a little bit of context is in order. Look at Tyrod's stats the last three weeks:
week 15 MIA 17/29 224 1 TD 0 INT
week 16 at NE 21/38 281 0 TD 0 INT
week 17 at MIA 19/27 204 1 TD 0 INT
So not quite as bad as you make him out to be, but he also won't be confused with Drew Brees, Aaron Rogers, etc.
In my opinion, either you keep Tyrod and get rid of Dennison, or vice versa. Personally, I think we need to move on from both. Get a vet like Alex Smith and draft a QB this year. That to me would be the best scenario; we'll see what happens.
I just hope they'll let Tyrod be Tyrod more and win a couple of playoff games. Dennison has yet to do that this year so far.