Part of Reed's problem is his blocking is terrible. He had the DE on that fourth-and-one pitch to Rex, and if you notice, his man made the tackle, preventing Rex from getting the outside.
Reed has significant lapses in blocking, and in this offense, that's a huge problem. However, I think we're misusing Reed, since we constantly put him in a key blocking position at the point of attack and not Cotton. Cotton is the best blocking TE, so we throw him the most passes. Reed is the best pass-catching TE, so we have him block all the time.
Makes no sense.