Most sports games try to reproduce the experience of watching the sport on television. An important part of that experience is hearing the announcers' commentary, or play-by-play. Most TV and radio sports broadcasts include at least two people, the play - by-play announcer and the color commentator. The play-by-play announcer describes the action on a moment-by-moment basis. The color commentator, usually a retired coach or player, offers insights into strategy and tactics, as well as background material on the teams or individual athletes. To make the player feel she's right there in the stands, you might include a third voice, that of the stadium announcer over the public address system. His remarks tend to be quite formulaic, although they do occasionally include requests to move badly parked cars, retrieve found children, and so on.
To study what kinds of things your audio commentary will need to do, record a TV broadcast of a real match and then transcribe everything that is said and who said it. Do this for two or three matches, and you will begin to notice patterns in the play-by-play: The announcers tend to read out the score at particular times, they use certain repetitive language, and so on. As you watch the match on videotape, take note of the different kinds of events that occur and the different remarks these events elicit from the commentators. The events that provoke a reaction from the color commentator aren't necessarily the same events that trigger a response from
the play-by-play announcer. The color commentator speaks at more dramatic moments or when an athlete has done something particularly spectacular (or particularly bad). For example, in tennis, you might have a color comment such as, "She's having a terrible time with those double faults!" when an athlete commits four double faults in a single game. Remember, a commentator would use this line only once, not after every subsequent double fault.
When you need to create commentary for a set of match events, sit down with the programmers and discuss the events to make sure the software can detect them. Some, such as a strikeout in baseball, will be uncomplicated, but many events will be judgment calls. A dropped pass in football that the athlete really should have caught, for instance, is not so easily detectable; you can detect the dropped pass, but what determines whether the receiver should have caught it? The probability of the receiver's catching the pass must be calculated from such things as the receiver's dexterity rating and the accuracy with which the quarterback threw the pass in the first place—provided that the ball wasn't tipped away by a defender. It's always best to err on the side of caution in these cases: Don't design judgment calls that the player is likely to disagree with, or he'll think you've delivered a stupid game.
As the saying goes, "It's better to remain silent and be thought a fool than to open one's mouth and remove all doubt."
Don't forget the introductory and wrap-up material at the beginning and end of the match—commentary such as, "Welcome to Invesco Field for today's game between the New England Patriots and the Denver Broncos. It's a cold and windy day."
For more detailed information on writing commentary scripts, including the many tricky issues associated with assembling commentary out of speech fragments, read Chapter 13, "Interchangeable Dialogue Content," of Game Writing: Narrative Skills for Videogames, edited by Chris Bateman (Bateman, 2006).