The Los Angeles Rams are uncertain when or if quarterback Matthew Stafford will return this season, league sources told ESPN.

Stafford is out Sunday against the Kansas City Chiefs because of a strained neck and two recent trips to the concussion protocol. He suffered one concussion earlier this month, and the Rams never could prove he suffered a second concussion even though he was in the protocol a second time.

Stafford, 34, has absorbed plenty of physical punishment this season. On Wednesday, the Rams ruled him out for their game against the Chiefs.

Rams coach Sean McVay said Stafford felt some numbness in his legs after taking a hit last Sunday against the Saints but also emphasized that even though Stafford is in the concussion protocol, it doesn't mean he has been diagnosed with a concussion.

Stafford's status going forward is similar to that of injured Rams wide receiver Cooper Kupp, who was expected to miss six to eight weeks after having ankle surgery. Sources told ESPN the Rams, who have lost four straight games and six of their past seven, feel there is no need to rush back an injured player unless the season stops slipping away.

If the Rams (3-7) can string together some wins, starting Sunday when quarterback Bryce Perkins is expected to start at Kansas City, then they can have Stafford rested and ready for a stretch run.

Perkins is a 2020 undrafted free agent from Virginia who has shined during the preseason but not gotten extensive playing time during the regular season. Perkins' first NFL start could not come in a more difficult venue -- in Kansas City against a Super-Bowl contending team.

Sunday's game could be the first of multiple starts this season for Perkins, depending on how he plays, how the team fares and how Stafford recovers. McVay said Wednesday that he would not rule out shutting down Stafford for the rest of the season, saying the Rams "are not going to do anything that's reckless."

Stafford has passed for 2,087 yards, 10 touchdowns and eight interceptions this season, his second with the Rams.

John Wolford started under center for Los Angeles against the Arizona Cardinals in Week 10 -- the first game Stafford missed while in the concussion protocol -- but Perkins replaced the injured Stafford last Sunday against New Orleans, completing 5-of-10 passes for 64 yards while also rushing for 39 yards.