Bulaga's position is more important for the Packers offense, and TT has had a harder time filling it. That said, if they went to the draft for Cobb's replacement it would be at least a year before the replacement was ready to contribute at Cobb's current level. It is possible that a healthy Barclay could replace Bulaga and do an adequate job, but that leaves them awfully thin on the OL. My answer to the OP question is a resounding "yes!"