Recently Moose told me about webarchive so I've been looking up some archived pages for stats.
This is the boxscore for Sampras-Agassi from Wimbledon.org, archived at http://web.archive.org/web/199911221...14/0127ms.html
Whoever produced it made no effort to distinguish between types of errors, because the Unforced Errors leave virtually no room for forced errors: if you add up the Unforced Errors to the Winners and the double faults, you have almost exactly the Total Points Won.
And we know that NBC put Sampras at only 22 unforced errors.
The non-service winners implied in this boxscore – by subtracting the aces from the total winners – line up with my own count. Wimbledon.org, unlike NBC, didn’t have a category for service winners; or if they did, they didn’t include them in their row for “Winners.”
Service winners are, of course, a type of forced error; and in this chart the forced errors have all been collapsed into the Unforced Error category. Strange as it sounds, that's where the service winners appear in this box: as Unforced Errors.
I have Sampras at only 16 aces (what I call a service winner, they called his 17th ace). And I’ve got him slightly lower on service percentage. But all the other counts I did – the totals points won on serve, break points, and Agassi’s service percentage – all agree with this boxscore.
Note that the Winners category includes service while the Unforced Errors do not appear to include the double-faults. The double-faults need to be added on top of the Unforced Errors and the Winners in order to approximate the Total Points Won.
However, even then there is not an exact alignment, because adding up all those categories would leave Agassi a little bit short with only 83 points won, and Sampras slightly over the top with 107.