In the comics, is Sentinel a lot larger and more massive bot than Prime. I just finished the Keepers prose trilogy by David Cian and its based off either DW or IDW continuity. Optimus is confronted with a replica of Sentinel built by the Keepers and Sentinel is described as a giant, taller than prime with trunk legs and a massive chest and powerful arms and voice so deep is shakes the ground. It seems as if Optimus in his mind struggles to live up to Sentinel. It certainly wasn't the Scientest/Warrior Sentinel from Dark of the Moon.