I don't think people understand the grooming process potential head coaches go through. Sean mentioned how he was a Quality Control coach and most people don't realize what that designation is. A Quality Control coach is a young coach who has been identified by the FO as a potential future HC prospect. They are exposed to all the aspects of the game that a HC needs to understand. The vast majority of the candidates don't ever make it in the NFL, but it's a huge thing to have on your resume if you are looking in the college ranks. It usually is given to a young coach that has "connections" to the NFL, but it's more than a simple ceremonial position. They will often rotate through the various positions as an additional assistant coach and it's there that the coach many times will focus upon the area he wants the expertise. In Sean's case it was WRs and RBs.
Sean has the pedigree but he still had to prove his chops and did. Stop and think about how close he was to being the 49er head coach which probably would have meant that Kyle Shanahan would then have been the Rams HC. Snead scooped the 49ers on both McVay and Stafford. This is why IMO Snead has got to be considered one of the best GMs of the Rams. It's why those 49er fans who know the history are doubly incensed over the Stafford bamboozle and why it made winning that Lombardi so much more sweet.