Harbaugh's lack of a great network (being a special teams coach and because he has only coached on 2 NFL teams) and the fact that he is fiercely loyal even if at the cost of improvement means he'll promote from within.
Seriously? Pretty sure almost anyone in the NFL would recommend one of their guys to work under Harbaugh, and he's worked with or for many of the best/well connected coaches in the league. Kubiak, Roman, Pees, Caldwell, Leslie Frazier, Steve Spags, Trestman, etc... all guys from outside his immediate coaching "tree" that have come to work for him. In several cases former HC's coming in as assistants or position coaches just to do so. Add to the fact that Belichick recommended him for the coaching hire here and his close relationship with Andy Reid, plus all the guys that have been promoted to other jobs after working under John... Harbs is probably just as well, if not more connected throughout the NFL coaching circles than anyone else. Connection to Spags means hes got connections to the Giants and the Coughlin tree. Connection to Kubiak he can tap Denver. Caldwell and Teryl Austin in the Lions. Pagano to the Colts staff. Reid to the Chiefs staff. Pederson at the Eagles. Belichick and Pees for the Pats. Frazier now gives him ties in Buffalo. Not to mention he can lean on Ozzie and the FO's connections for relationships with Hue Jackson and the Browns, Marvin Lewis and the Bengals so by association Gruden and the Redskins as well as Zimmer and the Vikings; Del Rio and the Raiders, Mike Pettine, Rex Ryan, Mike Smith , Jim Schwartz at the Eagles, Ken Whisenhunt, Mike Nolan, and a slew of guys present and past both pro and college like Mangini, Cam Cameron, Neuhisel (sp), etc... Include his brother Jim and his connections from both playing days, coaching in the NFL, and NCAA which go nearly as deep; plus his father whose contemporaries/buddies influenced an entire generation of coaches -- Harbs is easily one of the most well respected, well liked, and well connected guys in the league. He could make a call into almost every NFL organization and a wide range of the NCAA game and get the blessing to interview who he wants, or be able to talk to a trusted confidant to get a recommendation.
Your response is just a massive brainstorm. You are essentially saying that everyone in the NFL is connected to everyone. This is somewhat true however the previous posters were making the point that Coach Harbaugh went from being The Eagles special teams coach to a head coach with the Ravens. That Eagles job was his first job in the NFL. There's no doubt that he has hired more people connected to the eagles than any other franchise. Would it surprise you to know that Frazier and Spagnuolo all were with Harbaugh in Philadelphia. We all know about Juan Castillo. Harbaugh even loves Eagles players even the washed up ones like Jason Babin whom he chose over Dwight Freeney. In terms of connectivity the senior Harbaugh was never in the NFL. He was at Western KY university in Bowling in Green as a head coach and an assistant to Bo Schembechler at university of Michigan. The Harbaugh family is an excellent family, and a great great football family, but in NFL sense as a coach, John Harbaugh is the most accomplished. In my opinion I think he had too much affinity for everything eagles, and that's not using the full breadth of the NFL