Lucky for us there are people who actively keep track of such things:
— The data used is simply active players on NFL rosters. It doesn't speak to the quality of the player. A lot of that is subjective anyway.
— There are 28 active players in the NFL from Missouri. That number is 19th overall, exactly where it should be as the 18th most populated state.
— There are 14 players from schools that I would consider commonly referred to as STL-area schools.
— There are nine players from schools that I would consider Kansas City area schools.
— The rest of the state, including Jefferson City, Rogersville, Lebanon, etc., has five.
— For context, Miami has 41 players currently in the NFL from just 18 different schools. Miami, population 463,000, and Kansas City, population 488,000, essentially has the same population.
Belle Glades Central a public school just north of the Everglades, with an enrollment of 992, in a city of 17,000, has had 23 players in the NFL and currently has five.
The small agricultural communities in central and south Florida (Homestead, Immokolee, etc.,etc.) consistently produce more football talent than any other place in the country per population.
Those communities are also among the poorest in Florida.
That's the raw data.
My theory on outdoor athletics and successful athletes is simple, hard times + warm weather = tough athletes.
That's true in football where the poorest communities in the south produce a lot more talented athletes than their more comfortable counterparts in the north.
And it's true in a sport like baseball where small island countries with small populations and virtually no resources, produce more than a quarter of all the players in MLB.
It's true in track and field where small island countries do considerably well given their population in comparrison to their counterparts at the Olympics.
And, while I know less about it, the same probably true in a sport like soccer as well.
Your pop numbers for KC mean nothing. It is a metro area with 2.1 Million.