There are 32 teams in the NFL and about 4 quarterbacks you can say are "elite". The other 28 teams try to handle a guy that's below that level and win it in other ways, like on Defense and on the Ground. It's a shame that Mark isn't one of these special guys, but I'm not sure why anyone assumed he would be.
Mark Sanchez doesn't have a single WR that has spent back-to-back complete seasons with Mark Sanchez bonding or developing that unspoken chemistry that turns bad playcalls into plus yardage. He doesn't have a dump-off RB. I can't think of a single QB in the NFL that wasn't given one of those.
You might be right, Mark Sanchez might suck and that's that. Or, it may be that Mark Sanchez has been mishandled and needs a competent OC under a realistic HC with a supportive GM.
We're going to find out. No need arguing over it.