IT depends on the QB and the circumstances. Flynn had several productive games in relief in 2013, notably the second half against Dallas and I think the Pittsburgh game IIRC. He also had a monster game against Detroit in 2011 which got him starting money from a genius GM somewhere else.
You have to be a simpleton to put everything on Stubby. Like most very successful coaches he has many strengths, but also some limitations, and he is also limited by the personnel he gets, which is affected by the teams' success. The comprehensive big picture matters.