The Seahawks made the roster moves on Tuesday. They also released fullback Eddie Williams and signed defensive end Jameson Konz off the practice squad.
McCoy suffered a knee injury early in Sunday's 30-28 loss to Atlanta when teammate Aaron Curry crashed into his right leg on punt coverage. Coach Pete Carroll said Monday that the team didn't believe McCoy's injury was season-ending, but placed him on injured reserve a day later.
Vobora was with Seattle during training camp before being cut at the end of the preseason. He previously played with St. Louis.