The way I look at it, Our back up Qbs are insurance.. in case something happens to starting QB... and our back up has to be ready to play in the game. I would never want injuries to happen to any QBs, no matter what their role is... the thing is, If we're up by 21 points, and it's early in 3rd quarter... score is 21-3. We put in our back up Qb, and he get hurt immediately on next play. What do we do? We put back our Starting QBs in the game? or go to the next back up Qbs? I would rather bring our back qbs in slowly over the years until the starting QBs leave and they can step in with confidence knowing they can get the job done.
So you want our starter to play in the same situation you fear the backup getting injured in? That makes no sense.