The difference as I see it, is that Tannehill does try to get the ball down the field more. He doesn't go through progressions well, and tends to throw to the first read...or just throws to spot without checking the defense. He does not fake well at all, but since we don't have a running game...it might not do much.
Henne, on the other hand, checked down way too much. He still does...look at some Jags tape. Henne goes through the progressions, but his concept of "open" is simply not on par with the better NFL QB's...he over-manages the game. I think this was due to Sparano...and his stupid clock!
Both had issues with the deep ball. I actually think Henne was better in this regard...the issues with Tannehill and the deep ball are glaring!
The biggest problem with Henne though was his reads. I think it was the Pats game that I gave up on him. He simply couldn't read a zone blitz. It was pathetic. All you had to do against the guy was drop and LB now and then, and you would end up with the ball. I haven't seen that problem with Tannehill. He still has issues, but he is only in his second year with a TERRIBLE OL.
Now...with Henne, I was patient with him until his 3rd year. I am doing the same with Tannehill. I haven't made my mind up yet, because he is showing progress. Henne didn't show that.
But, to be clear...if he stays at this level and does not improve next year...he is not "the guy." The level he is an now, is not acceptable.