Maybe the Texans and Eagles are trying to find the next McVay type. Get away from the tried and true. I wish teams would start hiring the Niners coaches. Saleh is a big start but how about some offensive assistants? McVay is running out of friends to hire and the quality since his first staff on offense has been slowly eroding.
Good camparisons as Nick Sirianni reminds me of Adam Gase because I believe the Eagles hired him due to the high praises of Philip Rivers and the fact that maybe they wish they had kept Frank Reich.
David Culley seems to have put together a decent staff, although I have doubts with Lovie Smith because it's been 9 years since he's been a DC. Robert Salah brought with him Mike LaFleur (Passing Game Coordinator) & 49ers Offensive Line Coach John Benton, so they lost 3 assistants and two main guys on offense, that's a good thing.
As to McVay's staff, I will have to analyze once it's done and you could be right because Barry & Pleasant were excellent position coaches, but I believe Morris & DeCamillis were great hires, now we have to see how the rest of the staff works out before we can pass judgment.