It looks like the media process is much stronger in Philadelphia, where Ron Rivera is found giving quotes about other team's staff, and where our new DC Sean McDermott gives interviews better than we'd see here.
McDermott, on staff throughout Andy Reid's tenure there,was apparently notified about his release quietly to save face. Then, Reid attempted to cover the firing, contacting Rivera to setup the possibility of a lateral move, a move Rivera welcomed. It would save face for McDermott, a move instead of a firing, until the news leaked.
article here: http://www.philly.com/philly/sports/eagles/115461824.html?cmpid=15585797#ixzz1DJs6IBVa
McDermott also interviewed with John Fox in Denver, but it's not known if that was prompted by Reid as well.
It suggests that while Reid himself may have not been happy with the defense, he may have been persuaded to make change he wouldn't have otherwise made. Reid had suggested only days before that McDermott would stay. Follow that with attempting to cover up the firing, and it certainly doesn't look like an angry scapegoating at the least, and certainly shows Reid's respect for the young coach.
It also seems that Reid either didn't have a plan for the new staff, or those plans fell through. Dick Jauron made sense as a successor, but may have opted out. Jim Mora, Jr didn't come aboard. After a long purge of staff, they ended up with their own OL coach, an unprecedented move (the quoted move of Ravens coach Mike Nolan from WR coach to DC was clearly a move to stash the respected coach to let Marvin Lewis leave, which they did without missing a beat). If Castillo had been the choice all along, why not just hire him later that week and hire assistants?
McDermott was validated a bit with the Packers' win this week: his Philly squad held Green Bay to its lowest yardage total of the postseason. The Packers went on to dominate post-season offensive totals but only put 309 yards on the Eagles.
Also, since he interviewed with the team (which looks like they're trying to increase visibility, that article is here: