In hand to hand combat, being angry actually helps in some situations. In a professional setting in combat sports, anger usually does not help as it muddles the brain. This can mean the difference between winning and losing, as a clear head is the most important when you are against an intelligent trained individual who is looking for vulnerabilities.
In an untrained setting, anger towards a person increases ferocity. There is a saying that the person is the most brutal and fierce is likely going to be the person that emerges as the victor when it comes to brawls in the streets. A person fueled by rage and uncontrollable malice will have an upper hand on the hesitant individual.