Sports such as wrestling, football and boxing, can have a lot of aggressive tactics used in order to win, however I don't believe that should be categorized as violence. These tactics, such as punching the head in boxing, tackling in football, and body slams in wrestling are legal in the sport and have strict rules to prevent injury. I believe that violence in sports is doing things that are frowned upon or illegal in sports.
Most athletes tend to care most about winning; winning brings success, something that athletes strive for. Depending on the person's morals and values, the athlete may choose to do violent things because they want to win so badly, and doing so may give them the upper hand'. An example would be hitting someone in the back of the head in boxing. This is considered illegal and I would say violent. A reason why someone would do this could be to heavily weaken or daze the opponent, and hope not to get caught while gaining an advantage. Athletes may resort to violence, just to win in the sport.
With winners, there must be losers; losing is something some athletes may not enjoy. Losing can cause the competitor to rethink how they play their sports, or cause a whole lot of anger. Depending on the person, if he/she gets angry because they lost, they can outlet the anger back into sports. For example, Mike Tyson bit off Evander Holyfield's ear in the third round of their rematch. I believe he did this act of violence because he was angry at losing the first 2 rounds in the judge's scorecards.
Violence does play a roll in sports, mostly...