Here's another story / data point: Years ago, I was trying to learn to water ski. For some reason, I was struggling more than most. My buddy that was teaching me kept telling me what I was doing wrong but I just couldn't stop (I was pulling the rope in towards my chest). He finally put duct tape around my elbows so I couldn't bend them. It worked immediately and I was water skiing the first time I tried it with duct tape. Once I knew what the correct way felt like, I obviously never needed to duct tape my elbows again.
Having that been said, some really good players have all kinds of bad form (Keith Mcready & Alan Hopkins come to mind), and those guys will run balls up your wazzo with that bad form.