Sports commentators can help viewers know what is going on on screen, when something is difficult to see, but they can also be distracting. Do you like listening to commentators, or would you rather they weren't on?
It depends which sports it is. I think teams sports such as rugby need commentating to help you know who is in possession of the ball, etc. I also like commentators on Formula 1, who inform you of off screen events.
I don't much care for commentators in tennis though. A lot of them just waffle on non stop about absolutely pointless stuff.