Raiders coach Jon Gruden said Tuesday that he feared McCoy had suffered a "long-term" injury, the same day it was revealed that right guard Denzelle Good had suffered a torn ACL in his left knee and was lost for the season.
McCoy and Good were placed on injured reserve Wednesday. The Raiders signed defensive tackle Damion Square and guard Jordan Simmons in corresponding moves.
Square, who was on the Chicago Bears' practice squad, played for Raiders defensive coordinator Gus Bradley with the Chargers. Simmons, who was on the Seattle Seahawks' practice squad, began his career with the Raiders as an undrafted free agent in 2017.
The Raiders also made a move on their practice squad, signing veteran safety Ha Ha Clinton-Dix and releasing cornerback Madre Harper.
Defensive end Yannick Ngakoue (hamstring) and backup quarterback Marcus Mariota (quad) were also mentioned by Gruden as being injured.
For McCoy, 33, it is the second straight season the six-time Pro Bowler has had his season end early because of injury. He suffered a ruptured right quadriceps in training camp with the Dallas Cowboys in 2020 before signing a one-year, $1.25 million free-agent deal with Las Vegas on Aug. 4.
McCoy played nine defensive snaps against the Ravens -- a 33-27 victory -- and went down on a 49-yard pass from Lamar Jackson to Sammy Watkins with 6 minutes, 31 seconds to play in regulation before being carted off the field.
NFL Network was first to report that McCoy was lost for the season.
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