While I know these players are very talented their nervousness and inability to relax is causing them to play well below their ability. Coach Gary McKenna Dear Gary, A players excitement level is unique to each individual. In sports psychology this is often referred to as activation level and is described by what is called the Inverted-U Hypothesis. A players ability to relax and concentrate will be affected by the amount of activation. Too little activation, poor performance, too much activation also poor performance.
Some teams are very hyper, others almost too calm.
However you must also be aware of each players activation level. Try to find a method to approach each player prior to the game and identify key points and what you want them to concentrate on during the game. How you communicate this information depends on their alertness, activation level, and response you want to elicit from them during the game. I think it is also important to get players who, are anxious and cannot relax, to focus early in the game on successful execution of one skill. This might be to specifically concentrate on stopping their defender three times in a row down the court, or working hard physically to get an easy lay-up for their first shot attempt.