I posted in another thread my concern with the face mask in the dallas game and a drop in performance since then. Remember, last time manning screwed up his neck it wasn't 1 hit in particular, it was the slow nerve degeneration after multiple hits that eventually got so bad in 2010 that he was playing the worst of his career.
My concern immediately after seeing his neck pulled to the side two weeks ago was "****, I hope that doesn't cause him more nerve damage." And I think it's a legitimate concern, even though he finished that game strong. Time will tell, I guess, but it's something to keep an eye on.