It is interesting. I have seen a few different results caused by anger. I know this guy who is a pro, who gets himself fired up and angry on purpose in matches because he knows when he is angry and amped up, he focuses better and plays better. It helps him get super focused and use the anger. Now I think this guy is a little rare. Most people won't play better when they are angry.
I know another guy who is close to the same level and when he starts getting angry, he will blow a bunch of points in succession and get more and more angry as he loses his composure and stops being able to focus on the match. For him, anger is not such a good thing.
Now, I have to admit, I don't fully understand it and I don't know that I have much that would be useful. Anger really does not come up for me as an issue. If I mess up, I might react, directly after for a moment. Not too often, but I might. But, then, once the next point is going to start, it is gone and I am focusing on the next point. There is no room for holding onto anger or anything from the last point when I am focusing on the next point.