Can't speak for coach but in his book he believes that the typical shelf life of a HC with an pro team is four years after which the lack of new material makes the job more difficult because things become stale and opponents understand your philosophies and have built counters. So going on that I think he thinks that Jeff's energy and love of football and people will radiate through the organisation and locker room.
As for the discipline and being unselfish. Coach has a very strong beliefs that staff is there to support players and that they should be front and center. I see this that his "concern" is that Jeff being very charismatic and open will create a situation where he becomes the face of the franchise and cast a shadow over the players and that is something that would not be accepted, also makes reference of culture and landscape which ties into this as well.
As for the discipline issue. Jeff has a history of getting others in hot water with some of his public comments. It isn't done with that intent but the man is a free bird and absolutely no interest in the politics around him. H's a pure football coach.
The best example I can give you is a snippet he posted on one of his social media accounts last year.
Jeff Reinebold THE ROAD HOUSTON...UPDATE....[b]TOM MASON CALLED, THERE IS A BIG JUCO NT OUT THERE SO I AM OFF TO CHASE HIM DOWN IN THE MORNING....TOM SAID THE ALABAMA COACHES TURNED HIM ON TO THE BIG FELLA AND NOW WE GET TO SEE IF HE CHECKS OUT....MARSHALL, IOWA STATE, KSTATE AND TROY ARE SUPPOSED TO BE BEATING DOWN HIS DOOR...[/b]HUNTINGTON, AMES, MANHATTEN OR ? WHO EVEN KNOWS WHERE TROY IS OR DALLAS...HUM...THINK IT IS TIME TO PONY UP!
These kind of posts seem harmless but they drop names, sources and recruiting activity that brings heat on the people your work with and for. That's what Coach could mean by discipline. Its ok to be excited and share with the fans but anyone who follows our team know that the culture and landscape does not work that way...
Now this is just my perspective on things. I think he will be very helpful to our players and popular with fans and media, he's a cool guy but he will need to be mindful of those around him and work within the structures of the club "go in the same direction" you could say.
Could also refer to putting your knowledge and activity in reports and documents that the rest of the staff can work with. A lot of guys are great football minds but don't document it well and it ends up causing chaos for others who have to spend a lot of time trying to figure things out.