McVay told reporters that he is not sure if Stafford has a concussion, per The Athletic. Stafford's injury currently is deemed a neck issue as the Rams continue to gather more information.
McVay added on Wednesday that Stafford experienced numbness in his legs after a hit during last Sunday's game, which led to further testing Monday. The coach also hasn't ruled out the idea of shutting down his starting quarterback for the remainder of the season, per The Athletic.
While McVay didn't commit to a QB for Sunday, backup Bryce Perkins appears on track to start. NFL Network Insiders Ian Rapoport and Tom Pelissero reported earlier Wednesday that Perkins was expected to receive the majority of first-team reps this week. John Wolford, who is dealing with his own neck injury, was limited at practice on Wednesday.
Stafford started the Rams' Week 11 loss to the Saints, but was knocked out of the game following a sack early in the third quarter. He did not return to the game, which was the Rams' fourth straight defeat.
Perkins, who replaced Stafford at QB after that, is in line to make his first NFL start this Sunday at Arrowhead Stadium. Perkins completed 5 of 10 passes for 64 yards and ran five times for 39 yards against the Saints, which was only his second regular-season appearance of the season.
After winning the Super Bowl last season, the Rams have fallen to 3-7. Cooper Kupp, Stafford's most trusted receiver, is on injured reserve due to an ankle injury. Injuries, drama at running back and limited returns from some of the Rams' newcomers have all proven to be major concerns this season.