23rd is a fair ranking for Sanchez. He's never shown the consistency that a top QB should. Poor completion % and too many turnovers (both INT's and fumbles). His third down completion % has to get better as well to keep the drives going. Far too many 3 and outs on a regular basis.
Sanchez has to improve on all these things. He doesn't have as good a supporting cast anymore so the team is far more dependent on his play for success.