Not sure how it affects his technique, but my guess is it would almost surely affect his training. Tough to keep working with heavy weights if you have a degenerative back condition.
Some people have.
I am thinking of him specifically, not some people. Some things he has that present problems for someone in his position is his age. Not that he is old but that he is likely as far a long as natural growth will take him and improvements at this point will likely be less than they would for a man 5 years younger. Another is his back condition that may or may not be negatively affecting him as well. I am not a doctor but some doctors thought it was serious enough for him not to be allowed to play in college. A few things are often listed and described as not something that can be taught or developed one is height and another is speed.
I have not seen anything from him so far that would indicate he will be anything other than just a guy on the team. It is not his fault that he was picked where he was. He seems to be a very good teammate and generally the type of guy that one likes to have on your team from an attitude and type of person stand point. I am not expecting much from Jarvis at this point and expect he will be a less valuable player than Vince Williams. I suspect with Jarvis we will have taken a very good back up player who will be here a while and we will need to be finding a replacement for him soon in the starting line up.
if he did not get hurt he could have anywhere between 6-10+ sacks he had 2 after 2 games, he can tear up bad LT's its he needs to bulk up muscle wise and create a few different pass rush moves like the swin move and bullrush to get sacks, he in the 2 3 starts and 2 sacks used speed to get his sacks, its time Peezy teaches him how to be a OLB like how he was.