Well, I'm sure he won't, but he's not listed as being injured in the pre-game report: http://www.mlsnet.com/games/02/previews/0912dcmet.html Maybe he just retired instead.
Maybe they are pullin another surprise! Like the Diallo "out for 3 weeks" ankle. They will wait till juuuust the right moment and slip Balboa onto the field. They tried to do it with Mathis after the world cup but got snagged. ;-)