Maybe Mularkey was overruled on his plan to keep starting JP by old Whitey! ... I suspect the Bills will try to see if Holcomb can give their season a spark over the next few weeks, and if he fails, the team will go with JP the rest of the way.
Unfortunately, JP is not responsible for poor blocking and shoddy tackling --- which are big reasons the team is 1-3.
I wonder how the hell the Bills can spend five years trying to put together an offensive line. I swear they go out of their way to get guys that can't block.