I'm all for overreactions, that's part of being a fan. To me, I don't think we saw anything new yesterday. We knew this is a good, but inconsistent team and although frustrating, this is who they are. Which can still last a long way considering the quite mediocre 2012 team won it all by getting hot at the right time.
Regarding Mitchell's low usage - I haven't tried re-watching the game, but I noticed during the broadcast that I saw him badly miss on a pass blocking rep where he started going right, then moved back in, and ended up blocking no one despite a lot of rushers. In a game where Jackson is already running for his life, that might have been a reason for limiting his playing time. Blitz pickup is hopefully something he'll learn over time.
Better luck on Thursday, I hope.