Does seem to be an issue at times with many athletes doesn't it. One of the best pieces of advice is on using breathing to create relaxation and focus. I suggest these two because often early in the game guys on the hill may not have the focus they have in mid game. Energy is pumping, the situation is new, etc.
You may find these following articles helpful. The first is written by a sports psychologist out in Utah.
Clear the Mechanism
The below article written by the same guy has some more information. (The first two questions would be applicable to you somewhat.)
http://www.thepitchingacademy....Q_&_A_With_Justin_Su'a.html
Can't figure out the url deal, just copy and paste the above.
Nate