I give Smith all the credit in the world for soldiering on, and he's made some improvements in his game, but even if he didn't have the whole "seven offensive coordinators in seven years" thing hanging over him, it wouldn't change the fact that he's basically only capable of a limited number of throws from about 15 yards in. It's easy to say that Smith has been having a phenomenal season, numbers-wise, but that's traditional numbers based upon having a running game, run-blocking offensive line (Oh, God, imagine Cutler behind that line), and coaching staff that's superior to everyone else in a passing-oriented league. His advanced numbers only take some of that context out and they drop him into the average to slightly above average (12th in DYAR, 20th in WPA, 15th in PFF player grade, and so on). Using some common sense for team context drops him even further.
I do wonder what he'd be if he hadn't suffered that shoulder injury.
In any event, look at it this way: Smith is going to get cut (no one will trade anything substantial for the last two years of that contract) and the dude is gonna get paid
, considering how many teams are desperate for quarterbacks. Look at the paydays that Matt Cassel and Kevin Kolb are getting, for Christ's sake.