That's the second time Joseph's pulled the "I'm not going to make a change at quarterback if we're only two scores down" card, & it's completely ludicrous.
If a QB throws six picks in the 1st half, but the defense has a pick-six, a scoop & score, & a couple of amazing goal line stands, I'm gonna go ahead & NOT give my crappy quarterback credit for the defense's amazing play, & I'm going to put in a QB who MIGHT NOT: 
Imagine pressure when it's not there, & be oblivious to it when it IS.
Causing him to take off running when he shouldn't, and not run when he SHOULD. 
Have absolutely NO internal clock, leading him to get sacked on plays where he had PLENTY of time to find an open receiver. 
Lock down on his primary receiver virtually every play. 
Throw CONSISTENTLY off target even when he has a clean pocket to step up into. 
And, make HORRIFIC decisions that lead to picks, AND, lead the league in DROPPED picks.
SADLY, the two last are our supposed to be our starting QB's STRONG points.