Because if you ever watched Pennington play you would know he made up for his lack of arm strength with his ability to read a defense then get the ball out with timing. He did complete 66% of his passes for his career despite having a noodle arm, especially after the shoulder surgeries. Cam has relied on his legs most of his career and you could tell that the mental aspect was giving him some trouble in NE. His shoulder injury has changed his abilities. When your body starts breaking down then it is your wits that carry you on. I have never seen Cam be one to dissect a defense.