Just when you think you know who the elite teams are, college football surprises you.

It's just a matter of when. Turned out, Week 6 was full of those surprises.

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Iowa State turned the College Football Playoff picture on its head by upsetting No. 3 Oklahoma 38-31 in Norman. The Sooners fell nine spots to No. 12 after the loss.

This could go down as one of the most memorable upsets in recent memory – the Cyclones were down to their third-string QB, Joel Lanning rewrote the rules of positional versatility, and perhaps most impressive of all… Iowa State did this on the road. Big upsets happen. But usually, the underdog feeds off of its home crowd to stun the heavy hitter. Not this time.

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What does this mean for the Big 12? Well, if it’s going to send a team to the College Football Playoff, it will probably be TCU. The Horned Frogs fended off West Virginia 31-24 on Saturday and rose to No. 6 in the rankings. TCU trails one team from the ACC, Big Ten, and Pac-12, and sits behind two SEC schools. If the Frogs run the table, they’ll likely make the Playoff. Key word: likely. Someone ranked ahead of them should stumble, given the unpredictable nature of the sport. Bottom line: the Big 12’s margin for error is small. TCU faces Oklahoma on Nov. 11 in Norman, which figures to be a huge matchup.

The other big Week 6 upset came in Ann Arbor, where Michigan State took down No. 7 Michigan 14-10. For their efforts, the Spartans make their first AP Poll appearance of the year, coming in at No. 21.

The Wolverines, on the other hand, slipped 10 spots to No. 17. Michigan’s defense is still good, but it just can’t seem to figure out the quarterback spot. John O’Korn threw three interceptions and failed to crack 200 passing yards. The running game was anemic, too; it took Michigan 39 carries to reach 100 yards. Essentially, the defense is a force, but the offense doesn’t have an identity.

The Big Ten crown was already Penn State’s to lose, but Michigan’s loss solidified that notion. The Nittany Lions rose to No. 3 after demolishing Northwestern in Evanston. They have a huge stretch coming up – Penn State takes on Michigan at home in two weeks before traveling to Ohio State on Oct. 28. If the Nittany Lions can come out of that unscathed, they’re golden. If not, the Big Ten could find itself in a similar position to the Big 12. If you’re Ohio State, which checks in at No. 9, this thing is far from over.

Elsewhere in the rankings, No. 8 Washington State continues to dazzle. The Cougars easily could have faltered at Oregon after a thrilling win against USC last week. Didn’t happen. Wazzu controlled the game start to finish, and the Cougs are on a collision course with Washington to determine who represents the Pac-12 in the Playoff. The Apple Cup is always exciting, but this year’s version will be the most hyped it’s ever been. The Huskies are ranked fifth and were one of the last four teams standing last season. Football is back in the pacific northwest.

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A few notes from further down in the rankings: No. 16 Notre Dame and No. 20 North Carolina State were a few high risers. The Fighting Irish took care of business against North Carolina on Saturday to improve to 5-1. Notre Dame might have the best ground attack in the country – it ran for 341 more yards in Chapel Hill. Deon McIntosh and Josh Adams combined for 242 of them.

The Wolfpack, meanwhile, handled Louisville and reigning Heisman winner Lamar Jackson with ease Thursday night. N.C. State has two big ACC wins, also downing Florida State earlier. Ryan Finley has been miraculous at QB; he has 10 TD passes and zero interceptions. That’ll play. Ever since their season-opening loss to South Carolina, North Carolina State is averaging 37.4 points per game.

Teams 23-25 are new: Stanford, Texas Tech and Navy, in that order. The Cardinal scored a massive road win at Utah. Bryce Love continues to show why he’s the most dynamic running back in the country not named Saquon Barkley.

College football is predictable in one sense – you know crazy upsets will happen. But it’s also unpredictable in another sense: you don’t when they’ll happen.

And that’s the beauty of it. Iowa State will never forget that performance. Neither will Oklahoma, for the opposite reasons. Chances are, an upset of that caliber will happen again this season.

But where, and when? We’ll have to keep watching to find out.

Joe Boozell has been a college basketball writer for NCAA.com since 2015. His work has also appeared in Bleacher Report, FOXSports.com and NBA.com. Joe’s claim to fame since joining NCAA.com: he’s predicted the correct national championship game twice… and picked the wrong winner both times. Growing up, Joe squared off against both Anthony Davis and Frank Kaminsky in the Chicagoland basketball scene. You can imagine how that went.