It's hard to see in .gifs because they're so choppy. If you look at the first clip up there you can pick up where he drops his hand real low. Also on the 12th post you can see his hand drop upside down like that nad he is late and behind the receiver.
It's something that is correctable with work. Bortles fights it and has been going to work with Tom House during the offseason. After his second season in which he threw for all those yards and touchdowns he thought he had it corrected and so he didn't work with House after 2015. His throwing motion was terrible last year and he struggled mightly with accuracy. He said he would be back working with House this offseason.
The funny thing is guys like him and Franks could probably throw it 20 yards with a flick of their wrist. But they have tought themselves this motion and it's a hard habit to break. Franks will get away with it against lesser competition in college but the better teams will eat him up. He'll pad his stats against the creampuffs but LSU, FSU and better teams like that will pick him off.
Threads with lots of gifs can definitely get choppy on a phone. They play fine on a computer with a decent amount of memory.
You make a great point about Franks throwing motion. I went back and watched each clip full screen on my computer. It appears that it is something the coaches have been working on cleaning up. Franks will get his hand up near his ear on some throws and other times he holds it down. It doesn't appear to have a clear pattern, except he got his arm up every time he was trying to put some touch on the ball.
Clip 1 - The ball travels 5 yards past the LOS with lots of zip. His arm definitely goes down. The ball is on his hip as his arm goes backwards. The result was a good pass that was ever so slightly high.
Clip 2 - The ball travels 4 yards past the LOS with good velocity. His arm stays high and the ball is just under his shoulder as his arm goes back. The result is a good pass that hits Powell in the stomach. The pass was a little late, but I think that was Franks being hesitant to throw before he sees the receiver make the cut.
Clip 3 - The ball travels 37 yards past the LOS. His arm goes down and the ball is just above his hip as his arm goes backwards. The result is a beautiful pass that hits the receiver in stride. As you stated, it's probably more necessary to get a longer wind up when throwing deep.
Clip 4 - The ball travels 14 yards past the LOS with lots of velocity. His arm goes down and the ball is even with his hip as the arm goes backward. The result is a ball that is slightly high and behind the receiver. I think there is a chance that Franks thought the receiver was going to turn towards the pylon. If so, this may have been a catchable ball.
Clip 5 - The ball travels around 3 yards through the air with touch. His arm stays up and the ball is even with his shoulder as his arm goes backward. The result is a nicely thrown swing pass. The ball is on target and easy to catch.
Clip 6 - Sack
Clip 7 - The ball travels from one hash to the other side of the field. His arm goes down and the ball passes by the bottom of his rib cage as he winds up. The result is a dump off pass that is fairly on target, but is incomplete. The ball was chest high when it got to the receiver, but the angle made it a really tough pass to get past the defender. I think the only way this goes complete is if Franks lofts it over the receivers head.
Clip 8 - The ball travels 6 yards past the LOS with lots of zip. His arm stays up and the ball passes by his shoulder pad on the way back. The result is a completion that was just a little high, but hit the receiver in stride. As NavetG8r pointed out earlier, the pass was probably high because Franks was throwing over the Ref.
Clip 9 - The ball travels 15 yards from the LOS with good velocity. His arm stays up and the ball passes by this shoulder pad on the way back. The result is a beautiful pass. The ball hits the receiver in stride and right in the chest.
Clip 10 - The ball travels 2 yards past the LOS with touch. His arm stays up and the ball passes his shoulder pad on the way back. The result is a scrambling dump off to Callaway that is perfectly thrown.
Clip 11 - The ball travels 3 yards past the LOS. His arm stays up and the ball travels past his shoulder pad on the way back. The result is a well thrown catchable ball that is dropped. The ball was in front of the receiver and at upper chest height..
Clip 12 - The ball travels 4 yards past the LOS with good velocity. His arm drops and the ball passes just above his hip on the way back. The result is a pass that is slightly high and behind the receiver.
Clip 13 - The ball travels 2 yards past the LOS with good velocity. His arm stays up and the ball passes by his shoulder pad on the way back. The result is an incomplete pass that was thrown too hard and high.
Clip 14 - The ball travels 18 yards past the LOS with good velocity. His arm stays up for the most part and the ball travels just under his shoulder pad as it goes backwards. The result is an absolute beautifully thrown ball that hits the receiver in the chest.
Clip 15 - The ball travels 5 yards past the LOS. His arm stays up and the ball travels past his shoulder pad as it goes back. The ball would have hit the receiver in stride and in the gut if it were not for the referee standing there.
Franks arm went down during the windup on 5 of 14 passes. By my count, when his arm went down he was 2 of 5 for 45 yards (40% completion rate). When he kept his arm up he was 6 of 9 for 74 yards and a TD (67% completion rate). That is a significant difference in accuracy.