One of the main reasons Jimmy Johnson had so much success with the Cowboys is because he had extensive personal knowledge of a majority of the best college players due to recruitment research while he was a college coach and coaching with and against them. When he came into the NFL he not only had personal knowledge of the players best suited to his systems and style of coaching but also had a lot of college coaches and personnel connections. That information helped him with building our dynasty team of the 90s. When he later went to Miami, he was unable to duplicate that success because he had no longer had that personal knowledge and had to rely more on team scouting and personnel departments like most teams.
Pete Carroll had no real success in the NFL prior to the Seahawks because he worked his way up to head coach. By then, his personal knowledge of college players would have been limited due to being out of the NCAA for a few years. With the Seahawks, just like Jimmy did with the Cowboys, he went straight from college head coach to NFL head coach so he fully retained that knowledge and information.
It's the same with Jim Harbaugh with the 49ers. He went straight from college head coach to NFL head coach and had success.
Now this is not meant in any way to belittle the accomplishments of any of those coaches because the NFL has been filled with direct-college-to-nfl head coaches who had little to no success. Carroll, Johnson and Harbaugh are/were all very good coaches. I just don't believe they would be able to duplicate that success if they were to switch teams unless they went to a team already filled with talent.
What I'm really looking forward to is the post-Brady Belichick era. Belichick was average or worse prior to Brady so it will be interesting to see how he does when Brady's days are done.