The toughest tests have been passed, the tallest hurdles cleared for Texas, Alabama and Florida. For the second season in a row, an SEC-Big 12 matchup in the BCS championship games seems inevitable.

Maybe too inevitable?

With Iowa out of the unbeaten picture, Florida and Alabama might even be able to stumble a bit down the stretch and still play for a national championship.

That’s not really the way the BCS is supposed to work.

The Bowl Championship Series hasn’t had a season without controversy surrounding its national title game since 2005, when Southern California and Texas romped to the Rose Bowl as the only undefeated teams in college football.

That was as good as it could get for the BCS. The undisputed best teams in the country in a matchup that could not have happened in the old bowl system.

At least some of the pieces are in place for another gripe-free title game in Pasadena, Calif.

Unbeaten Texas has a smooth road ahead, nothing but double-digit underdogs await — including, most likely, in the conference title game. Win out and Colt McCoy and the Longhorns head back to the Rose Bowl to try to win another title for Texas.

Florida, which beat Oklahoma in the BCS title game last year, and Alabama already have booked a rematch for the Southeastern Conference championship game. The key is for the Gators and Crimson Tide to get to Atlanta undefeated, which would for the second straight year create a national title play-in game at the Georgia Dome.

Iowa’s 17-10 loss to Northwestern on Saturday dropped the Hawkeyes from the ranks of the unbeaten, trimming the number of teams that could go undefeated and be left out of the national title game to three — namely Cincinnati, TCU and Boise State.

The outrage over the Bearcats, Horned Frogs and/or Broncos being shut out of the BCS title game in favor of undefeated SEC and Big 12 champs would be relatively mild compared to say the furor that rose from the South when prefect Auburn got left out in 2004.

But there’s another scenario developing that has to make the folks who support and promote the BCS uncomfortable.

Could Florida or Alabama lose a game and still reach the national championship game ahead of an unbeaten team?

One of the arguments against a playoff is that it could render late-season games meaningless because top teams would have already secured spots.

But if Alabama loses a close game to Auburn in its regular-season finale, then goes on to beat No. 1 Florida and earn a trip to the title game on Jan. 7 ahead of unbeaten Cincinnati — or maybe even unbeaten TCU — hasn’t the Iron Bowl been rendered, essentially, meaningless?

And if that’s the case, well then there’s one less reason to defend the BCS.