I have been meaning to look up some causes of tennis elbow in golfers. I thought I remembered something having to do with too much elbow flexion during the backswing, which I believe is also a big cause due to the rapid elbow extension during the downswing and at contact. In looking for additional information, I came across this article below. This makes a lot of sense – avoid cupping that lead wrist to decrease wrist extensor activity through the swing. It all comes back to the basic tenet of keeping joints as close to neutral as possible.