Koets played eight games (four starts) in 2010 before suffering a torn anterior cruciate ligament in a victory in Seattle on November 7. He underwent surgery and was placed on injured reserve.
The Oregon State product was placed on the reserve/PUP list in July 2011, and suffered a back injury during the course of his rehabilitation.
Koets has played in just 11 games for the Giants over four seasons (2007-10).
The Giants also signed defensive end Craig Marshall to the practice squad and terminated the contract of fullback Alex Daniels.