The Sentry is a puppet. He is as powerful as Robert Reynolds imagines him/it to be. If Bob has doubt or fear within him, and feeling particularly agoraphobic on any given day, the Sentry will not be as powerful, and when he is easily defeated in combat, it is just Bob retreating from the world. Therefore he has no true base level. We've already seen him die, rip himself apart, molecularly dispersed, or at least partially. Death holds no meaning to him, or at least it didn't in the past. So unless there has been a retcon on the character, the above picture is meaningless. He has no true base level.