For the most part, sports commentators are morons. That's a big reason why I like going to actual games a lot better than watching them on TV. The mute button comes in handy too.
The basic problem facing your typical sports commentator is how to make himself (usually a male) even remotely useful since most games are self explanatory once you understand the sport. Home runs, yellow cards, sacks, three pointers and other important moments generally don't require the subtle eye of a veteran broadcaster.
King Kaufman has a whole article about announcers this week and he brings up the classic commentator lines about "knowing how to win" and "having confidence".