2. Vrabel is a former player
Vrabel is, of course, a former NFL linebacker who played eight seasons in New England under Belichick. So, he learned quite a bit from Belichick. But, at the same time, Vrabel understands the game from a player's point of view, which is valuable in today's league.
Not only does he understand the game from a player's point of view, but he's quite a bit younger than Belichick and has been able to better understand how the game has evolved from today's player's point of view.
If you look at many of the league's top coaches and coordinators these days, there is a good amount of them who were NFL players at one point. Whether or not they were good players is another conversation, but in today's NFL, it is a huge advantage for a player to know their leader has been right where they currently stand.
This current generation of players, just like today's society, is very self-centric. They need to see proof before doing something. They need to know that others know where they're at and what they're going through on a daily basis. It's just how human nature has evolved, and that's another reason why bringing in Vrabel would benefit this team, especially the younger guys.