Can a sport team "clinch" a championship in the last regular season game?

Here is the entry for the transitive verb clinch in Merriam-Webster's Eleventh Collegiate Dictionary (2014):

clinch vb [prob.alter. of clench] vt (1542) 1 : CLENCH 3 ["to set or close tightly"] 2 a : to turn over or flatten the protruding pointed end of (a driven nail); also : to treat (as a a screw, bolt, or rivet) in a similar way b : to fasten in this way 3 a : to make final or irrefutable : SETTLE {that clinched the argument} b : to assure the winning of {scored a touchdown to clinch the game}

If you think of a team's season-long effort to earn a place in the league's postseason playoffs as contest to win such a spot, then the moment at which the team is assured of playing in the postseason is the moment at which it clinches the spot—and that can happen when the team wins the final game of the regular season, or when a combination of events play out in its favor (for example, it loses its final game, but so do the other three teams that were in contention for the spot, allowing it to back in to the playoffs). Indeed, if the league used a coin flip to determine which of two teams that were tied in the final regular-season standings should get a spot in the playoffs, you could say that the favorable coin flip clinched the lucky team's place in the playoffs.

It's true that a team that can get into the playoffs only if several other teams cooperate by losing can "assure the winning of" the playoff spot for itself in a rather odd way; it might be truer to say in that scenario that it can "be assured the winning of" the spot—which does stretch definition 3b slightly. But definition 3b of clinch isn't the only available meaning of the word. Definition 3a seems to permit the use of clinch to mean "settle or decide in one's favor, regardless of the means by which the settling occurs."

As for the argument that clinch means something like "ensures the desired outcome, regardless of what competitors do," that definition would seem to forbid using clinch in a situation where two teams tied for a final playoff spot are playing each other in the last game of the season—since in that case the team that wins makes the playoffs only because the other team loses. A similar notion is at work in this example from Russ Hodges, Baseball Complete (1952):

The gifted run permitted the White Sox to down the Giants 4-2 in the 1917 World Series clincher and stamped Heinie as a bit of a blunderer. Truth to tell, Heinie was absolutely blameless. His mates had left home plate as unprotected as a cat at a dogshow and poor Heinie could find nobody to throw the ball to. So he set out after Collins in futile flight.

Here, the clincher is the deciding game of the baseball World Series. The White Sox won it and the Giants lost it, but the clinching occurred at the moment that the World Series (and the 1917 baseball season as a whole) ended.