The man who said, “Leave your customers wanting more” didn’t work for the NFL.

The league that owned Sundays in the fall annexed Monday nights on Sept. 21, 1970, when Joe Namath and the New York Jets played the Browns at Cleveland’s Municipal Stadium.

That venture proved to be a smashing success. But it wasn’t enough.

Fans needed to be fed “Sunday Night Football’’ and the occasional Saturday games late in the season. They were. But that wasn’t enough.

Four days between games seems to be the quickest turnaround the league can enforce and still keep a straight face while claiming player safety as is its No. 1 priority. So Thursday football became a weekly routine rather than a yearly tradition in Detroit and Dallas.

A Thanksgiving night game was added. Not enough.

A slate of Thursday night games in the second half of the season was added. Not enough.

Finally, every team in the league would play a Thursday night game each season. And now, for the first time in maybe forever, the NFL appears to have reached the saturation point where it has to be asking itself “too much?” as opposed to “not enough?”

Cleveland kicked off “Monday Night Football’’ with great fanfare in 1970. Those of a certain age now have to wonder what the late Howard Cosell would have thought 46 years later when the 0-9 Browns lost 28-7 to the 4-4 Baltimore Ravens in prime time a couple of Thursday nights ago.

Back in the day, the one prime-time game of the week was to be earned. It was a traveling party that went from city to city, celebrating the best teams, the best matchups and, at halftime, the best and only nationally-televised highlights of the games played the day before.

With television ratings for NFL games slumping, one can’t help but wonder if uninteresting preseason games are the only inferior product the NFL needs to be concerned about.

Through 11 weeks, “Thursday Night Football’’ typically has been a dismal matchup of teams that never would have earned the right to play under the moonlight of prime time years ago.

“Me, personally, I think it does kind of hurt the product,” Vikings receiver Jarius Wright said.

“People kind of don’t want to see the sorriest teams, the worst teams, play. We do because we’re NFL players, and we enjoy watching football. But everyone that doesn’t enjoy watching football or is not from the state of the team that’s playing, they might not want to watch the toilet bowl every week.”

Since Week 2, there have been 10 Thursday night games featuring teams playing on four days rest. Half of those games have had two teams with losing records. Nine of them have had at least one team with a losing record.

And in the only game featuring two teams with winning records, the 2-0 Texans lost to the 2-0 Tom Brady-less Patriots 27-0.

Not exactly Must-See TV, eh?

“Guys aren’t going to want to watch the Browns and some three- or four-win team,” Wright said. “I can understand that.”

The Wall Street Journal has taken notice of the lopsidedness of Thursday night. Through Week 10, it noted that the average Thursday night contest was decided by two or more scores 43.7 percent of the time, while all other games clocked in at 31.1 percent.

The WSJ also noted that Thursday night featured an average of 2.9 turnovers compared with 2.6 for other games, and 1.11 coaching challenges compared with .54 for other games. So maybe the officials are tired on Thursday nights, too.

“It’s definitely a quick turnaround for a player,” Vikings cornerback Captain Munnerlyn said. “We know what we signed up for, but it’s still tough to get your body going and to get up for those Thursday night games. We do the best we can.”

No one questions that. But is the best on Thursday night good enough to keep from tarnishing the league’s precious shield?

The average margin of victory on Thursday night is 13.7 points. There have been victory margins of 27, 21, 16, 15 twice, 14 and 12.

“I like playing on Thursday night,” Munnerlyn said. “But I guess for some teams it kind of hurts the ratings. I guess nobody wants to look at some of these games, huh?”

If that’s your guess, Capt., the guess here is you’d be right.

In the early days of prime-time football, “Dandy Don” Meredith would sing “Turn out the lights, the party’s over” once the game’s outcome was obvious. If he still were with us and doing Thursday night games, Dandy Don might be singing, “Turn out the lights, nobody’s watching.”