If you're familiar with baseball, you've seen Nomar Garciaparra and his extensive pre-at-bat routine that he does with his batting gloves. Though it may look somewhat ridiculous to those watching the sport, Nomar and other athletes who utilize pre-performance routines have learned about an important aspect in being successful in sport. Such routines help prepare the athlete mentally for sport. The body begins to recognize the habitual behavior done prior to every activity (whether it's an at-bat, a free-throw in basketball, or prior to swinging a golf club) and helps communicate to the body to start to focus. It's not necessarily what's done in the pre-performance routine -- the importance is that it's positive (if you talk to yourself, it better be positive) and that it is consistent. Pick a routine and stick with it, whether your past swing/shot/etc was successful or not. As a result, you'll find the improvement in your focus and mental preparedness will eventually result in more consistent performances.
"If something works why fix" is my motto when I get involved with competitive sports.
Pre-performance routines are applicable to any activity from theater to pitching product to a group of suits. One can win just by being prepared.
I had a doubles partner in racquetball who would redo my grip wrap before every tournament whether it was needed or not. We always won.
In college softball, I would always hit the bat on the inner side of both my shoes before going to bat. It relaxed me and helped me prepare for the pitch.
The routines are numerous. I bet some sports players are not aware that they do it.