Biscuitt may have shown some improvement from last year (we don't know that, I'm just conjecturing), but that's still not enough, he was so raw in his rookie season, that if he only shows some "improvement", that's not enough to play QB for this franchise that relies so heavily on precision and timing in the offense.
I wonder if he is not a better fit being a backup for Cam Newton or some other offense where he could use his skills better and not disrupt the offense. In this case with some positive notes from Belichick some other team could take a flyer on him for a 4th or 5th rounder. I can't see him being anything other than a backup in NE, and a Bryan Hoyer kind of backup, not Jimmy G type.