This speech is essentially idiomatic, widely accepted, and common to both sports professionals and enthusiasts, and therefore should be considered standard, or otherwise editorially acceptable.
In this instance, "finals" is short for "finals match" or "finals game."
Finals takes the plural in the context of tournament play as a result of there being multiple games or matches that are considered "final."
In tennis tournaments, for example, even restricting your consideration to the very last match of a bracketed contest, you still have multiple "finals" that include men's, boy's, women's, girl's, double's, mixed double's finals and so on.
But, the language of tournament play is actually not even that restricted. Working from the final end of a bracketed scheme, you have the final match, and prior to that, the semifinals, the quarterfinals, and octo-finals, and in some instances "double octo-final" rounds.
Any one of these games is a "finals game," which in common speech gets shortened to simply "finals" when talking about the World Cup, the NBA basketball finals, or the NCAA college basketball finals. I suppose that it is worth noting that this shortening and grouping is not handled exactly the same in all sports.
Requiring the use of the non-plural in this context actually introduces an ambiguity as to whether you are talking about the actual, ending match of the tournament, or one of the other matches in the "final brackets" of play.
In terms of the specific Wikipedia article. You could add "match" or "game" to the end of the sentence to eliminate the idiomatic shortening. This could easily be a justifiable editorial decision for the Wikipedia, but would certainly be of more questionable judgment for a sports journal.
That being said, I would take a look at the "highest" sports journal you can find reference to in terms of its editorial adherence to standardized speech and see whether match or game is more appropriate, and if you cannot find reference examples of the same context, then I'd feel quite comfortable leaving it alone.