This is where hypnotherapy can really help. You regress him back to when he was kicking great and feeling great about it. Then that hypnotherapist, also a sports psychologist, helps him to get everything off his chest. Then more hypnotherapy, boosting his confidence and feeling great about his kicking, visualizing perfect kicks over and over. Then immediately afterward, he goes onto the practice field with a trainer and just starts hitting those EPs and FGs over and over. Then his most recent memory is of nailing a ton of those in a row, and the game feels like a distant memory. Rinse and repeat, if necessary.
Don't laugh. It may sound hocus pocus, but teams do things like this successfully all the time. It works if it's a mental problem. If it's a physical problem, it won't work.