The Bills and McD hadn’t committed to Tyrod since before this season. So they were never sold on him. Tyrod was nearly a FA, they didn’t pick up the option. Tyrod chose to come back to the Bills while they were looking for other options. When he took a pay cut they probably figured, why not, and then let him see if he can run the offense they want to run.
It hasn’t worked, so on to Peterman the Bills go.