Why the starting time for the Oct. 21 Rams-49ers game was bumped from Sunday night to the afternoon

What looked like a gem of an NFL game six months ago is considerably less attractive now.

Rams at San Francisco is no longer a “Sunday Night Football” game.

That Oct. 21 matchup will be replaced on NBC by Cincinnati at Kansas City, pitting teams that are currently 4-1 and 5-0.

The Rams are the NFC’s only undefeated team, but the 49ers have dropped off sharply after losing quarterback Jimmy Garoppolo to a season-ending knee injury and are 1-4.

This is the first time the league has used its game-flexing policy this early in the season. Traditionally, the schedule shuffling takes place in the final six weeks of the season. A special provision was put in place after the 2011 season, however, when Indianapolis — which had lost Peyton Manning for what would be the entire season — was beaten by New Orleans 62-7 in a Sunday night stinker.

It wasn’t just that Rams-49ers was less attractive, but that both the Chiefs and Bengals have played their way into prime time, especially with the buzz surrounding Kansas City quarterback Patrick Mahomes.

Then again, the Chiefs are going to be on “Sunday Night Football” two weeks in a row, because they also have that spotlight this week at New England.

As for the 49ers, they will still get plenty of exposure, with three prime-time games in the next five weeks — two Mondays and a Thursday.

When the league flexes out of a Sunday night game, it gives that game to whichever network gave up the replacement Sunday night game. So that means Rams-49ers goes to CBS (which originally had Chiefs-Bengals). CBS already has Dallas at Washington — the result of a cross-flex with Fox — so it will have two marquee NFC games in that 1:25 p.m. national slot.

If Cowboys-Redskins turns out to be less interesting, or it goes quickly, CBS could wind up switching to the game in Santa Clara so the entire country can get a look at the Rams.

When the NFL makes these types of decisions, it doesn’t do so in a vacuum. So the league will be looking for a way to get the Rams back on national TV.

A couple of possibilities could be flexing the Rams into the Sunday night window when they play at Detroit in Week 13 (San Francisco at Seattle is slated for that Sunday night), or when the Rams play at Chicago in Week 14 (Pittsburgh at Oakland).

It’s highly unlikely the NFL would move Green Bay at Rams to Sunday night in Week 8. That’s the Fox national game, and the Sunday night game is New Orleans at Minnesota. That almost certainly will not budge.

sam.farmer@latimes.com

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