What he described doesn't need a scientific study to prove anything...so many factors go into a players shot....for instance if a player does the exact same movements from the exact same distance while shooting the ball....the ball will go in 10 out of 10 times. The reason players don't often shoot 100% is because its literally impossible to make the same exact miniscule movements throughout your body twice. That's why a player misses....because the same movement wasn't done as the one that made the ball go in. The most a player can hope to do is make nearly the same movements every time. So a player can get hot....because he really starts to feel it. Quite literally. His body is in rythym and he has more control of it than at other times. We all experience this in our day to day lives. Shooting is coordination. Coordination means that things in your body are working together. Some days they work better together than others. Confidence can have a huge effect on your coordination. Study any area of medicine....and it becomes obvious that the mind and our thoughts have direct and quite substantial effects on our body's behavior. This isn't hippy dippy shit. A person who really starts to feel it does so..because thier in the zone that day.... everything seems to be working together....because it is.