In this O-line scheme, it is enormously important that center make the right calls. Why was Max Unger so valuable? Cuz he new all the fronts and o-line calls. Its not surprising that o-line played better with Patrick Lewis than Drew Nowak. The center position is the most mentally difficult position out of all the offensive line positions. You really need seasoned veteran there. Every other lineman in Cable's system plays off the center.