Raiders head coach Jack Del Rio didn’t expect safety Nate Allen to take a bow on the 2015 season. The sixth-year veteran spent most of the year on the shelf with various knee injuries, killing the opportunity to finish this year on the field.

An injury-riddled campaign was formally concluded on Wednesday, when Allen was placed on injured reserve with a knee injury. Allen spent most of the year on short-term injured reserve after tearing his MCL in the season opener. He returned after eight games and played just four before aggravating the same knee.

Allen will miss the final four games of the year, making the four-year, $23 million contract an expensive enterprise without much in return. Allen was paid $7 million for limited services this year, and can be cut without adding dead money to the salary cap.

The Raiders could have to revamp their secondary this offseason, with Charles Woodson retiring, Allen’s contract flexibility and questions at cornerback beyond David Amerson and TJ Carrie.

The Raiders promoted cornerback SaQwan Edwards from the practice squad in a corresponding move. This marks the undrafted free agent’s first stint on the 53-man roster.