Let's go down the list, see what we see (coach, age of HC gig)
Shula - 33
Halas - 25
Belichick - 39
Landry - 36
Reid - 41
Lambeau - 23
Brown - 38
Shottenheimer - 41
Knoll - 37
Reeves - 37
Knox - 41
Fisher - 36
Parcells - 42
Coughlin - ancient
Shanahan - 36
Holmgren - 44
Ok, there's an age bias on # of wins, so how about win %, min 50 wins, circa ~1970 or more recent?
Madden - 33, coached under Don Coryell at SD State, defensive/linebackers (RIP)
McVay - 31, WR, coaching family, offensive
Shula - 33, DB, defensive
Belichick - 41, defensive
Dungy - 41, DB, defensive
Seifert - 49, linebacker, defensive
Tomlin - 35, college WR, defensive
Reid - 41, OT, offensive/QB
Payton - 43, college QB, offensive
Arians - 60! (although his first college HC gig was at 31), offensive, college QB
Martz - 49, TE, offensive
Cowher - 35, LB, defensive
Gibbs - 41, OL/RB offensive
Schottenheimer - 41, LB, defensive
Harbaugh - 46, DB, defensive
Walsh - 48, QB, offensive
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You ever go in expecting to find something and then you end up thinking about things more deeply?
No point here. I'm dialing back my Team Moore stance a little bit, although I do believe he will be a HOF head coach when it's all said and done.
I did a bit of a deep dive on these coaches and here were some interesting tidbits:
Walsh invented WCO in '68 for a talent-limited QB. Paul Brown blacklisted him as best he could across the NFL.
Reid showed up for his Philly interview with a 5" binder on his plan. His name came up when the owner wanted to know who players complained about the most as being 'too detail oriented'.
Shula, Walsh, and many other HOF HCs had military backgrounds.
Madden was pre-law and had a passion for teaching.
McVay and many others have coaching families (looking at you, Kellen).
There are a LOT of defensive types with the highest win %.
Many of these high win % coaches began as HC when they were young. Many began when they were around 40. Some when they were closer to 50. Those corner cases are intriguing (Coughlin, Arians, Martz, Seifert).
I haven't looked, but I bet if I did, these names might just be dudes who knew what to do when the right QB fell into their lap.
Ok, I'm curious now about that last conjecture. Nah. This is enough. Maybe someone can run that test for me.