1: Notre Dame winning out

Because only 4 teams make the playoffs, 1 conference is always left out of the Playoff. If Notre Dame wins out they would have wins over USC, NC State, who were ranked 11th and 14th respectively at the time of the win and Miami and Stanford, who are currently ranked 9th and 18th respectively and a win over then-unranked Michigan State, who is currently ranked 24th. Their only loss would be to Georgia, who is now ranked 2nd. From this information, I don’t see a case for leaving Notre Dame out of the playoff. However, if the selection committee selected Notre Dame, this would leave out another conference, so the playoff would include 3 Power 5 Conferences and Notre Dame. Notre Dame is an Independent, which means they do not belong to a conference. This means they can schedule tougher games to beef up their resume wins, but it also means that they can never win a Conference championship, which the committee has stated they value a lot. 

If Notre Dame wins out, the Conferences I see being left out are the PAC-12 and the BIG 12. I see these Conferences being left out because A; their preseason frontrunners have already lost, some more than once. In the PAC-12, USC lost to Washington State and Notre Dame. Washington State was destroyed by Cal 37-3 and Washington lost to Arizona State 13-7. In the BIG 12, TCU just lost to Iowa State, who has two losses on the year. Oklahoma was upset by Iowa State, (despite being a 31 point favorite) and Oklahoma State lost to TCU. 

2: Iowa State winning out (plus the Championship game) and TCU doesn’t lose again, while the PAC-12 Conference Champion has one loss

Let's pretend Notre Dame loses a few games. This would mean that only 1 conference is left out of the Playoff. Iowa State has 2 losses on the year, a heartbreaker to Iowa and a 10 point loss to Texas. However, they beat Oklahoma (then ranked number 3) in Norman 38-31, shocking the world, and just this weekend beat TCU (then ranked number 4)14-7. They have one remaining game against a Top 25 team, vs. number 11 Oklahoma State. The BIG 12 has brought back their Championship game this year, which gives the Committee an extra win to look at. If Iowa State wins out, they will be in the BIG 12 Championship Game. A two-loss team has never been in the College Football Playoff in its three year existence, and just last year, BIG 10 Champion Penn State, who had two losses, was left out of the Playoff for 1-loss Ohio State, because they had better wins. If TCU doesn’t lose again and Iowa State doesn’t lose, this sets up a BIG 12 Championship Game between TCU and Iowa State. Let’s say Iowa State wins. This would give each team two losses, and Iowa State the BIG 12 crown. Remember, Notre Dame has lost twice, and the PAC-12 Champion has 1 loss. In this situation, the committee would have to choose between a two-loss, better resume, Iowa State, or a 1-loss, worse resume, PAC-12 Champ.

3: NC State wins out (plus the ACC Championship)

NC State just lost to Notre Dame this weekend to give them their second loss. But if they win out, they would find themselves in the ACC Championship. If they win that game they would have wins over Florida State, Louisville, and Clemson, ranked 12, 17, and 7 respectively (at the time of the game). They would have a bad loss to South Carolina, and a loss to now-ranked 5 Notre Dame, plus another win over a good team from the ACC Coastal Division, most likely Miami. This would put the Committee at a tough decision whether or not to include a two-loss NC State team with good wins, but a bad loss early in the season. 

4: USC wins out and wins the PAC-12 Championship

USC has one good win; over Stanford (who was ranked 14 at the time). They have no bad losses, but losses to Washington State (who was ranked 16 at the time) and Notre Dame (who was ranked 13 at the time). They have one remaining game against a Top 25 team when they play number 23 Arizona next week. Besides Arizona their remaining games include; at Colorado, and vs. UCLA. If they win out, which is extremely possible, their final record would be 10-2 and they would have secured a berth in the PAC-12 Championship. That gives them an opportunity to get another win, most likely over Washington or Washington State (and maybe even Stanford, if they sneak in). If they win that, their resume would be 2-2 vs. Top-25 teams, no bad losses, and losses to Notre Dame (ranked 14 at the time) and Washington State (ranked 16 at the time). This would give the committee a hard decision of whether to leave USC out or the BIG 12 Champion, which could also have multiple losses. 

5: Auburn wins out and wins the SEC Championship

If Auburn wins out then they would have lost to Clemson (ranked number 3 at the time) and LSU while having wins over Mississippi State (ranked 24 at the time), now-ranked 2 Georgia, and the big one, now-ranked 1 Alabama. If Auburn beats Alabama and doesn’t lose to an SEC team, then Auburn would get the nod for the SEC Championship game, because they would own the tiebreaker over Alabama. If Auburn wins the SEC Championship Game, then the committee would either have to leave out yet another 2-loss team and arguably the best overall Conference in College Football out of the College Football Playoff, or put Auburn in, who would have a bad loss to LSU, a loss to Clemson, and 4 wins over the Top 25 (including the SEC Champ Game). 

6: LSU wins out and wins the SEC Championship

If LSU wins out they would have two bad losses. First, a 37-7 loss to Mississippi State, and second, a 24-21 loss to Troy, the worst loss a Power 5 contender has. However, they would have wins over Florida (ranked 21 at the time), Auburn (ranked 10 at the time) and, as we saw with Auburn, a win over now-ranked 1 Alabama. Like for Auburn, that’s huge, because that gives LSU the tiebreaker in the form of the head to head victory. This would send LSU to the SEC Championship, and if they were to win, that would give them another win over the Top 25. Like with Auburn, the committee would either leave yet another 2-loss team and arguably the best Conference in College Football out of the College Football Playoff, or put LSU in. 

7: Stanford winning out and winning the PAC-12 Championship

If Stanford were to win out, they would have losses against USC (ranked 6 at the time) and against San Diego State. But, if they win out they would have wins over Utah, Washington State, Washington, and Notre Dame, ranked then 20, now 25, now 12, and now 5 respectively. This would put them in the PAC-12 Championship where they would most likely get a win over another Top-25 team. Their playoff contention would come down to the committee, to see if they favor Conference champions.

8: Arizona winning out and winning the PAC-12 Championship

If Arizona were to win out they would have losses against Houston, and Utah (ranked 23 at the time). They would have good wins over Washington State (ranked 15 at the time) and now-ranked 17 USC. However, this means they would make the PAC-12 Championship, and if they win that, they would get another win over a Top-25 team. Again, their playoff contention would come down to the committee, to see if they favor Conference Champions.

9: All Power 5 Champions have two losses and the AAC Champion goes undefeated

This is a surprisingly possible situation that would give the committee a huge headache. Let’s see how we can get here. In the ACC, we come back to NC State. If they lose to Notre Dame, they would have two losses, but if they don’t lose to an ACC team they would make the ACC Championship, and if they win, that’s our first Power 5 Champ with 2 losses. In the BIG 12, if Iowa State or West Virginia win out, they will make the BIG 12 Championship, and if they win, we have another Champ with 2 losses. In the BIG 10, if Ohio State beats Penn State, that would give them the tiebreaker, and they could clinch the BIG 10 East the week before the final week. If they lose to Michigan the final week, it wouldn’t impact them in making the BIG 10 Championship, but they would have two losses. If they win, that’s our 3rd Champ with 2 losses. In the PAC-12, if Stanford, USC or Arizona wins the Championship that’s a 4th team with two losses. And if Arizona State wins out and wins the Championship, we have a Power 5 Champion with 3 losses. The SEC would be the hardest conference for this to happen. Auburn is our only hope for this. If they win out they would own the tiebreaker over Alabama for the SEC West, and if they win the SEC Championship, they would have two losses to Clemson and LSU. There’s our 5th Power 5 Champion, with 2 losses. UCF is the only undefeated Group of 5 team. If they win out they will make the AAC Championship and if they win, they may have a chance of making the Playoff.