What I notice is that his mechanics seem to change during games.
When he is comfortable, especially early in games, he almost seems to try to aim the ball and his delivery looks kind of funky to me. He doesnt play with that type of aggression in his mechanics that you tend to see late in games and in comeback situations - where he steps into throws and drives the ball down the field.
Yep; I've commented on the same thing. At times he tries to guide the ball, taking some of the velocity off the throw, usually with bad results. Haven't seen him do that for a few games now...
As for throwing off his back foot, Josh needs to be aware WHO he's throwing to; if it's a more athletic quick guy who can ADJUST to a throw, I'm fine with it. But Clark was heavily covered and simply isn't all that nimble or quick enough to react to an off-target desperation throw.