Isn't physical, maybe it's psychological. There was an older gentleman in our training class who simply freaked whenever the plane got within 50' of the ground. He was pretty good otherwise.

While all the discussions about technique are valid, maybe you should try being honest with the guy.

Ask him if he understands what's going on with the plane.

Ask him if he's scared/nervous/ashamed of his lack of skill.

Tell him you don't think its working with you and find him another instructor.

And, keep in mind that if you label him as "pathetic" on the boards, you may be transmitting that level of contempt to him at the field.