I dunno, living out in LA I watched a bunch of Sanchez in his one year starting at USC, and I was near positive that he would be a bust. To this day, I'll never understand how anyone watched his college tape and thought that he would be an effective pro QB. His only chance to make it as a pro would have been to go somewhere where his entire decisionmaking process could be broken down and reassembled, and at that point you kinda have to question if it's even worth the effort.
To the extent that he hasn't been awful in Philly--and he has been bad in a nearly QB-proof system that requires him to make zero complex reads or especially quick decisions--the little bit of good is still far outweighed by the unfathomably awful turnovers. He just sucks, and he always will.
I would agree that Tannenbaum coincided with hte high point of the Jet franchise, but it simultaneously must be acknowledged that the high point wasn't even all that good. A barely-over-.500 team twice got just a tiny bit hot, won a couple games, and made it a round or so further than they reasonably should have. That two year stretch would be considered the definitive low point over the past 15 years if it happened to the Pats.
I don't think Tannenbaum was the worst GM. Plenty of GMs have destroyed their salary cap, and he at least had a few good draft picks to go along with it. But if we're dishing out credit for the meager success that the Jets had from 2008-2011, even then I think Rex deserves most of it.