By happenstance, I came across the Wikipedia page for NFL coaches throughout history:
I realized something when I sorted the list by years as a HC. I made a Google Doc to track the stats:
There are only 25 coaches in the entire history of the league
that have more years as a HC in the NFL/AAFC.
That's not in the past 20 years, etc. In the entire history of the NFL,
Marvin will become only the 26th coach to accumulate at least 16 years as an HC in the history of the NFL when he finishes the 2018 season (and we all know he will).
So what of the 25 coaches that accumulated 16+ years of coaching?:
-- 23 of 25 of them had either a NFL/AAFC, NFC or AFC title on their resume. Only Marty Schottenheimer and Chuck Knox didn't.
-- And neither Chuck nor Marty did more than ten years as HC with any one team. Marvin has done this with ONE TEAM.
-- Every single one of them
had at least one playoff win.
-- And of course, it's already been publicized, but only Jim Mora matches this length of coaching without a playoff win. But a) he didn't get year 16 and b) never held that job with ONE TEAM for those whole 15 years.
Truly historic ineptitude here, folks. Who says Mikey doesn't like to achieve special things?
(I edited this to include the Google Doc).
(Edited a second time to make a note about Marty/Chuck).