When competing in such an elite organization of athletes like the NBA, the smallest details make a difference. For instance, it's the use of psychological combat. Players are ready to do anything to get into their opponent's heads to gain an advantage.
Rookies are especially prone to this because they are coming out of college as nearly unrivaled athletes, and now they're entering the league and competing with grown men. They'll often do stupid things in an attempt to throw off their opponents.
One example of this was Reggie Miller during his rookie year. Now, Reggie went down as one of the best shooters of all time, and he was no joke. However, as a young rook, Reggie was crazy enough to try and get into the head of none other than Larry Bird. You can imagine how that went, even without watching the footage.
This story comes from one of Reggie Miller's books when he talks about the Celtics and how they never overcame them during his first few years in the league.
It came down to a few points in one particular game, and Larry got fouled and was approaching the free-throw line. Reggie tried to throw him off as he was getting ready to shoot by saying something along the lines of "Hey, Hey, Hey!"
Larry Bird's response was,
Rook, I am the best f*cking shooter in the league. In the league, understand? And you're up here trying to f*cking tell me something?
Needless to say, Larry nailed both free throws and the Celtics won the game. Countless stories prove Larry Bird was a trash-talking genius, and this is just one of them, this time in the courtesy of Reggie Miller.