College football's tier of six and what it means for the CFP

Ohio State, Georgia, Clemson, Alabama, Michigan and Tennessee.

Call them the "tier of six," because more likely than not, the College Football Playoff will be made up entirely of that group this year, according to the Allstate Playoff Predictor.

After a wild Week 7, the playoff picture went from looking like three heavy favorites plus a wild card to six teams fighting for four spots.

Each of the six teams listed above individually has at least a 49% chance at the CFP, and every other team is below 12%. The chance that the CFP features four teams from that group is 62%.

In addition, the 14 most likely playoff combinations exclusively feature those six teams.

The playoff race isn't exactly just six teams fighting for four spots now. Undefeated Ole Miss (11% chance at the playoff) still controls its destiny and would even have an outside shot if it lost to Alabama and finished at 11-1 without winning the SEC West. Texas (8%) has two losses but could still have a chance if it ran the table, particularly since one of those losses was to Alabama. USC (8%) could win out and reach the CFP despite its loss to Utah last weekend. And TCU (6%) is undefeated, too, though FPI is slightly less of a fan of the Horned Frogs than any of the previously mentioned teams, so it thinks it's slightly less likely TCU can take advantage of its favorable position.

So all of those teams could work their way into the playoff. But they are not likely to. And again, the most likely result is that four teams from the tier of six end up in the CFP. Why is that, and what questions do we have about that group? Let's dive in.

Why does Alabama have a better chance at the CFP than Tennessee?

Alabama may have suffered a loss at the hands of the Volunteers, but the Allstate Playoff Predictor does not abide by poll logic. It's true that the Volunteers are undefeated and also could quite conceivably make the playoff as an 11-1 team with a loss to an eventual SEC champion Georgia (therefore likely besting an 11-2 Alabama team). But Alabama and Tennessee are not the same.

Despite Alabama's loss to the Volunteers, FPI considers the Crimson Tide roughly eight points per game better on a neutral field. Therefore, Alabama is just more likely to win games. It's close now, of course, but Alabama is still slightly more likely to reach the CFP.

Can Ohio State and Michigan reach the CFP together?

Absolutely. In fact, there's a 37% chance the two rivals both make it to the CFP, and five of the 10 most likely playoff combinations feature the two rivals.

The reason that number is so high is that both teams are significant favorites in every game until they face each other on Nov. 26 in Columbus, in a game Ohio State is a 75% favorite in, per FPI. If Michigan wins out until that game, then loses to Ohio State and finishes as an 11-1 non-champion, it would still have a 51% chance to reach the playoff. In a role reversal in which Ohio State lost to Michigan and finished 11-1, the Buckeyes would have a 68% chance.

Because of that scenario, there's a fairly decent chance they both reach the playoff and could even face each other a second time this season.

What's chalk?

While we can't lock in a result for every game -- that would create too specific of a scenario for the predictor to reasonably weigh in on -- we can narrow it down a lot. So let's try this chalky scenario:

• Georgia wins the SEC championship game over Alabama.

• Tennessee wins every game except for a loss to Georgia.

• Ohio State wins the Big Ten.

• Michigan wins every game except for a loss to Ohio State.

• Clemson wins the ACC.

There's a 1-in-20 shot that all of that precisely happens. If it does, Ohio State and Georgia are playoff locks, and there would be uncertainty over the final two spots.

Clemson would be a 65% favorite to grab one of the playoff berths, followed by Tennessee at 58%, Michigan at 41% and Alabama at 23%. In other words, if the chalk holds, it could create an awfully interesting scenario for the selection committee.