It's a common misconception that the Jets are exclusively a 3-4 defense. After watching tape of last years games against the Saints and Patriots, I noticed that Rex likes to use the 4-3 on obvious passing downs and long yardage situations. Not only will the Jets use more 4-3 in 2014, but they will be more effective at it and here is why:
1) Jeremiah George:
When the Jets ran the 4-3 last year, the third linebacker was usually either Garrett McIntyre or Calvin Pace. Sometimes Antonio Allen lined up there as well. McIntyre is generally decent at stopping the run but struggles in coverage. Calvin has no business lining up in that position either. He can't stop the run from that "Will" linebacker position and he is obviously very limited in pass coverage. I know I don't have numbers or statistics to verify these statements, but I am just merely telling you what I was able to observe from watching all the Jets games last season. Antonio Allen is a great run stopper for a safety, but lining him up at linebacker and expecting him to take on linemen is not a good idea unless you less you are absolutely sure he other team is going to pass the ball.
Which brings me to Jeremiah George who I think is going to be a steal. When the Jets selected Jace Amaro in the second round, I went back and watched Amaro vs Iowa State. Number 52 of the Iowa State defense was all over the field and even knocked a pass right infornt of Amaro. https://www.youtube.com/watch?v=jgx1M4BJw4c . The play I am talking about is at 2:52. I was very impressed with that player and looked him and learned that his name is Jeremiah George and the more I learned about him the more I liked. I was very excited when the Jets picked him up. He ran a 4.91 at the combine, but that's only because he had a tight hamstring. On his proday, he ran a 4.60. George fits perfectly in the weak linebacker spot. he can cover and he says that he prides himself in covering tight ends and receivers. He can also stop the run and shoot through the gap very well. I am telling you this guy is gunna see a lot more playing time than you think.
I am not even going to get into that. The obvious reason why we are going to be a solid defense on 4-3 plays is because Coples will get to play his natural position.
3) Calvin Pryor
Pryor, who can play both safety positions, will allow Rex to be able to play with more 3 safety formations. Instead of having Kyle Wilson in the slot, Antonio Allen or Calvin Pryor can now line up there and provide better run support. Kyle Wilson will be the slot guy on 3-4 formations and he will also be able to play in the 4-3 when the other team uses 4 wide receiver sets.
Demario is more of a 4-3 strong side linebacker than a 3-4 inside linebacker. 3-4 inside linebacker are expected to be run stuffing physical players like Harris. Davis just does not have that ability yet. Him lining up at the strong side plays to his strengths more as he is an athletic guy that can cover and stop the RB from bouncing outside.
The addition of Jeremiah George is a really underrated move and I believe that he is a special player that is going to make this defense a lot better.