John Abraham (concussion) to IR

— -- TEMPE, Ariz. -- The Arizona Cardinals have placed outside linebacker John Abraham on season-ending injured reserve because of a concussion, the team announced Friday.

Abraham, 36, had been going through the final stages of the NFL's concussion protocol since Monday but had yet to pass. On Wednesday, coach Bruce Arians said Abraham failed the protocol Tuesday and needed to wait 48 hours before he could try it again. Abraham didn't practice Wednesday or Thursday, spending the open portion of Arizona's practice riding a stationary bike.

Abraham then failed the concussion protocol again Thursday.

"The concussion protocol really did its job in coming back and finding a couple problems," Arians said. "The doctors feel he should shut it down for at least a year, and we're glad that we caught it now and not later."

Arians said Abraham being placed on the IR/designated to return list was not an option because doctors would not let him play for at least a year.

Arians was hoping to have Abraham for Sunday's game against San Francisco. He would've re-entered the starting lineup once cleared to play.

On SiriusXM NFL Radio on Tuesday, Arians said he thought the five-time Pro Bowler was shaken by the concussion, his first such reported injury according to ESPN Stats & Information. The NFL's active sacks leader with 133.5, Abraham will earn his $3 million salary by going on injured reserve instead of retiring.