[30gut]

To my eye Luck, Griffin and Tannehill are outstanding athletes for the QB position with very similar physical traits that separate them from the other QBs in this class. (excpet for Wilson but he has a different problem)

They all possess a skill that I think is critical when I look at QBs: playmaking, the ability to turn a negative play into a positive and in this regard all 3 are above average playmakers.
All three can throw very well on the run/move (which is a critically important trait that some elite QBs possess Drew Brees, Aaron Rodgers, Mike Vick, Ben Rothlisberger etc).
Luck, Griffin and Tannehill can can all extend plays with his legs by evading pressure and can also gain chunks of yards that extend drives with his legs.
Griffin's speed makes him the most dynamic but Tannehill is no slouch either having been a good WR and Luck is also an above average athlete too.

They all throw the ball well.
Griff has the best deep ball and Luck is the most consistent.
I think Tannehill has the best arm talent of the trio and can throw with more velocity then both Luck/Griffin.
I think they're about the same level in throwing motion.
I think Tannehill has a quicker release and a cleaner throwing motion then the other 2 but he sometimes throws from a 3/4 to almost side arm delivery which makes his throwing motion the least consistent.
(Or I think Tannehill has the best throwing motion when he's doing it right but he's not always doing it right.)

However their is a clear distinction or separation between Luck/Griffin and Tannehill.
Where Tannehill is raw Luck/Griffin are both high efficiency QBs that exhibit high level command of their respective team's passing offense.(But I would be remiss not to mention that both also have more offensive talent then Tannehill)
But imo the attributes that prevent Tannehill from being on the same tier as Luck/Griffin (i.e efficiency and command) are attainable through experience and coaching.