There is a great article in The New Yorker (May 26, 2014) that goes on and on as the articles in this magazine do. It is pretty extensive on the topic of ‘The Yips’. It is much like writer’s block and there are questions as to its origin. At any rate this affects the control of their shots.
Other names are “the jerks”, “whiskey fingers”, “the staggers”, “freezing” and “the waggles”.
Other sports are also affected, such as cricket bowlers, those who play darts, archery or baseball (going by different names).
For those suffering from this, the article is a great one.