For every one of his games as an NFL coach, John Harbaugh has employed Joe Flacco as his starting quarterback.

Now it's time for something completely different.

An MRI on Monday confirmed that Flacco tore the ACL and MCL in his left knee during the final minute of the Baltimore Ravens' 16-13 victory over the St. Louis Rams on Sunday.

It's a season-ending injury, so Matt Schaub will start next Monday night for the Ravens (3-7) against the Cleveland Browns (2-8).

The injury occurred after the Ravens recovered a fumble at the St. Louis 41 with 54 seconds left. On first down, Flacco fired an incomplete pass -- the last one he would attempt in 2015.

"I got hit right above the knee on my quad after I threw the slant," Flacco said. "My foot just stayed in the ground and kind of got collapsed in and just everything went."

Flacco and Harbaugh both made their NFL debut in 2008. They worked 122 successive regular-season games together through Sunday.

Protocol under review

The NFL is investigating whether correct concussion protocol was followed for Rams quarterback Case Keenum late in Sunday's loss at Baltimore.

St. Louis coach Jeff Fisher said Monday the system failed because of a "combination of unusual events" and believed that nobody in particular was to blame.

A league spokesman says Monday that a review began after the game to determine why Keenum was not pulled from the game after a tackle on which his head slammed against the turf. His hands immediately went toward his head, and he struggled to get up, appearing staggered.

Fisher said he didn't see Keenum's helmet hit the turf on a hit by Tim Jurnigan. He said he'd been in "game management mode."

"The appropriate thing is to get everybody together and just make sure it doesn't happen again," Fisher said.

•Meanwhile, the Texans said quarterback Brian Hoyer is done with the team's concussion protocol and will start Sunday against the Saints,

Osweiler, Part II

While Peyton Manning flew to Charlotte, N.C. , on Monday for a second opinion on his left foot, Broncos coach Gary Kubiak announced Brock Osweiler would get his second consecutive start this week.

Osweiler won his first NFL start Sunday, throwing for 250 yards and two TDs with no interceptions in Denver's 17-15 win at Chicago.

Etc.

•Running back Marshawn Lynch likely will miss a second consecutive game for the Seahawks because of an abdominal injury, meaning rookie Thomas Rawls will start for a second straight week, against Pittsburgh. Coach Pete Carroll said he is unsure when Lynch will play again.

•Carolina Panthers defensive end Wes Horton drew a four-game suspension from the NFL for violating NFL policy on performance-enhancing substances. Teammate Stephen Hill was suspended without pay for one game for violating the policy.

•The Jets waived linebacker Quinton Coples, their first-round draft in 2012. Coples played only five snaps on defense in New York's 24-17 loss at Houston on Sunday.