There are many reasons why a sportsperson might choose to wear a wrist support, not all relating to sporting injuries.
Information on helping recovery from injuries can be found at the NHS website.
One reason why a wrist support might improve performance is if you participate in a sport where the positioning of the wrist is crucial to the execution of the event you are involved in, such as gymnastics or bowling. In the latter case bowlers will use a wrist support to help increase their accuracy, but also to ensure consistency in delivery of the ball.
A bowling wrist support, such as those found at http://www.petesproshop.co.uk/acatalog/wrist-supports.htm could provide the answer for those looking to improve their strike rate.
Surprisingly, wrist supports are used outside of sport where repetitive movements can cause injury, such as in office work with keyboard operators, or in industries where wrists can become tender after continual movement in the same task.
Obviously, bowling involves similar repetition when executing particular releases of the ball to attempt a trike or pick up a spare. One of the benefits of using a wrist support is that it will minimise the pressure on nerves, which can be sensitive after making unnatural movements with the wrist.
Accuracy, however, remains the main reason a bowler will opt for a wrist support. Consistency in the moment of release of the ball is the aim of top bowlers and the support can help in this, by maintaining the position of the wrist on release of the ball.
Keeping the wrist solid and limiting movement ensures that finger and thumb movement on release remains constant. This is crucial as the thumb should always be removed from the ball before the fingers, and the support will help limit movement of the fingers in the delivery swing. This adds to the consistency of delivery for the bowler.
Bowlers will have to test different supports, and decide whether an adjustable or non-adjustable version suits them best and aids their release of the ball. Whatever feels most comfortable is probably the best choice, and this may involve also purchasing a liner for the support to minimise discomfort or chafing of the skin.
Whatever the reason for purchasing a wrist support, it is important that it feels comfortable once you begin a frame.