In this article, they touch upon how aggression is dealt with during a sports game. For some athletes, it can be the result of stress and pressure, and emerge in the form of venting. This will engage what the article calls "Hostile Aggression" and is described as having the intent of hurting or injuring another player/opponent. In contrast to this, the article also mentions another form of aggression that it refers to as "Instrumental Aggression." This form of aggression is encouraged in the game, and is all about the intent and control behind the specified use of aggressive force. if the goal or intent of the player is to win the ball, and not harm the other player in the process (in other words, controlled aggression within the limits/rules of the game), then it is proactive instrumental aggression and can be a valuable source of releasing stress and actually calming the mind. On the other hand, "harmful aggression" is a negative behavior. It is violating the agreed terms of the sport, as well as encouraging that kind of behavior in the aggressor.
Sports are very interesting because they are a physical activity that will require some form of aggression to succeed, especially if it's a contact sport. The psychological significance of this is pretty intriguing.