| Rank | Team | FPI Rank | POFF Prob | Change |
| 1 | Ohio State | 7 | 53.064% | -5.1% |
| 2 | Baylor | 2 | 45.247% | 9.1% |
| 3 | Mississippi | 1 | 37.582% | -8.9% |
| 4 | Notre Dame | 9 | 30.975% | -8.1% |
| 5 | Texas Christian | 8 | 26.320% | 0.2% |
| 6 | Georgia | 5 | 25.474% | -3.1% |
| 7 | Louisiana State | 6 | 17.911% | -2.9% |
| 8 | Oklahoma | 11 | 16.166% | -0.6% |
| 9 | Michigan State | 20 | 16.000% | -7.1% |
| 10 | UCLA | 12 | 15.407% | 6.8% |
| 11 | Florida State | 17 | 12.115% | -3.1% |
| 12 | Clemson | 15 | 11.888% | 3.3% |
| 13 | Texas A&M | 10 | 10.146% | 3.9% |
| 14 | Utah | 19 | 9.851% | 9.2% |
| 15 | Iowa | 38 | 8.388% | 4.8% |
| 16 | Southern California | 3 | 8.069% | 3.4% |
| 17 | North Carolina State | 28 | 7.860% | 4.6% |
| 18 | West Virginia | 13 | 7.795% | 3.3% |
| 19 | Wisconsin | 27 | 6.641% | 1.2% |
| 20 | Stanford | 16 | 4.256% | 1.1% |
| 21 | Michigan | 21 | 3.770% | 3.3% |
| 22 | Oklahoma State | 25 | 3.120% | 0.9% |
| 23 | Alabama | 4 | 2.972% | -0.4% |
| 24 | California | 24 | 2.931% | 0.6% |
| 25 | Northwestern | 41 | 2.744% | -1.7% |
| 26 | Florida | 23 | 2.384% | 1.8% |
| 27 | Toledo | 48 | 2.229% | 1.2% |
| 28 | Miami (FL) | 32 | 1.765% | 0.1% |
| 29 | Duke | 39 | 1.314% | 1.2% |
| 30 | Brigham Young | 46 | 1.220% | -8.0% |
| 31 | North Carolina | 31 | 0.843% | -0.4% |
| 32 | Texas Tech | 26 | 0.567% | -1.3% |
| 33 | Houston | 59 | 0.546% | 0.5% |
| 34 | Mississippi State | 22 | 0.522% | 0.3% |
| 35 | Kansas State | 36 | 0.379% | -0.2% |
| 36 | Temple | 57 | 0.330% | -0.1% |
| 37 | Tennessee | 14 | 0.255% | -1.2% |
| 38 | Penn State | 44 | 0.165% | 0.0% |
| 39 | Arizona | 37 | 0.165% | -1.9% |
| 40 | Georgia Tech | 18 | 0.115% | -2.1% |
| 41 | Memphis | 50 | 0.111% | 0.0% |
| 42 | Kentucky | 45 | 0.100% | 0.0% |
| 43 | Indiana | 71 | 0.069% | 0.0% |
| 44 | Virginia Tech | 33 | 0.048% | -1.4% |
| 45 | Illinois | 56 | 0.046% | 0.0% |
| 46 | Nebraska | 42 | 0.040% | -0.1% |
| 47 | Oregon | 35 | 0.027% | -2.9% |
| 48 | Pittsburgh | 53 | 0.021% | 0.0% |
| 49 | Missouri | 51 | 0.017% | -0.2% |
| 50 | Navy | 69 | 0.012% | 0.0% |
| 51 | Minnesota | 62 | 0.006% | 0.0% |
| 52 | Syracuse | 67 | 0.004% | 0.0% |
| 53 | Washington | 49 | 0.003% | 0.0% |
| 54 | Boston College | 63 | 0.002% | 0.0% |
| 55 | Colorado | 66 | 0.001% | 0.0% |
| 56 | Auburn | 34 | 0.001% | 0.0% |
| 57 | Arizona State | 54 | 0.001% | 0.0% |
| 58 | Washington State | 87 | 0.000% | 0.0% |
| 59 | Maryland | 85 | 0.000% | 0.0% |
| 60 | Oregon State | 82 | 0.000% | 0.0% |
| 61 | Wake Forest | 92 | 0.000% | 0.0% |
| 62 | South Carolina | 47 | 0.000% | 0.0% |
| 63 | Rutgers | 83 | 0.000% | 0.0% |
| 64 | Iowa State | 70 | 0.000% | 0.0% |
As you might guess, I have a few thoughts:
1. The carnage of September leaves us with precisely half of the teams we started the season with. Week four in particular rids us of seven teams, with the majority of the eliminated now hailing from major conferences. Let us bid adieu to Texas, Purdue, Virginia, Kansas, Vanderbilt, Arkansas, and Ohio. Arkansas is notable in that they are by far the highest ranked/best team to be eliminated (29th in FPI). What a year it could have been, Bert. Oh well.
2. As I guessed last week, the glut of big Pac 12 games in week 4 served to prop the conference up, nearly doubling their odds of producing a playoff participant. This may seem paradoxical, but it makes sense: Each conference game between top teams will produce a loss, but it will also clear a major hurdle for the victor, thus boosting their playoff chances to a greater degree than the loser is hurt. With UCLA and Utah as two of the biggest risers of the week, the conference is officially off of life support.
| Conference | Exp Playoff Teams |
| Big 12 | 0.996 |
| SEC | 0.974 |
| Big 10 | 0.909 |
| Pac 12 | 0.407 |
| ACC | 0.360 |
| Independent | 0.322 |
| MAC | 0.022 |
| American | 0.010 |
3. While the teams than won and lost big games moved predictably, a few weird things happened. Ohio State took a bit of a dip, in spite of staying roughly the same in FPI. There are two reasons for this. First, the issue I mentioned in the season preview of the playoff odds only summing to 2.5 instead of 4 is continuing to resolve itself. The raw playoff odds now sum to 3.1, an increase of 0.2 over week 3, which means that the multiplier of the raw odds is now slightly smaller. This will lead to teams being slightly more bunched together. Second, Michigan beat the crap out of BYU, and now has a 35% chance of knocking off the Buckeyes on Thanksgiving weekend, which is up significantly from 22% last week. The end result is that Ohio State isn't quite the runaway train I thought they would be. They're still number 1, so don't freak out. Or freak out if you want....it's fun for me to watch that.
4. Weird thing #2: Iowa is now #15 in playoff odds, sandwiched right between maybe the two most impressive teams of Week 4. Sure, their throttling of North Texas this week is better than the alternative, but that alone doesn't explain a near 5% jump in their playoff odds from last week. What also helps is that all three of the biggest remaining opponents (Wisconsin, Northwestern, and Nebraska) stagnated this week, such that Iowa is now ahead of all but Wisconsin in the FPI. The Hawkeyes are still underdogs in all three games, but now have about a 45% chance of beating Nebraska and Northwestern. If they can pull off wins in both of those games, they have a decent chance of finishing 11-1 and earning a date with whoever wins the other side of the conference. Stranger things have happened, I guess? (No, no...they haven't)
5. Weird thing #3: NC State continues to succeed in anonymity jumping up a similar percentage to Iowa. Their small jump in FPI (35th to 28th) combined with nothing special happening to their remaining opponents, and the general bloodletting of teams that actually played someone and lost in Week 4, leaves NC State in their best position of the season. I guess someone has to step up when others go down, and for now that team is the Wolfpack.
6. USC and Alabama continue to be two of the best teams in the nation, but their schedules will probably prevent them from making the playoff. Should either team make it to 11-2, we will be treated to a fascinating case study in how the committee deals with such a team. I would guess either (or maybe both) would be in at that point, but I have no idea, which is both exciting and terrifying.
September in Review
Now that we're a full month into the season, let's take a look at what's changed over the course of the season. Week-to-week variations are interesting enough, but taking more of a macro look at the proceedings should give us a better idea of what my model is doing. First, the teams with the most improved odds:
| Team | Current Odds | Original Odds | Difference |
| Mississippi | 37.58% | 6.60% | 30.98% |
| Notre Dame | 30.98% | 16.41% | 14.57% |
| Utah | 9.85% | 0.14% | 9.71% |
| Iowa | 8.39% | 0.53% | 7.85% |
| West Virginia | 7.79% | 0.96% | 6.84% |
| North Carolina State | 7.86% | 2.09% | 5.77% |
| Oklahoma | 16.17% | 10.45% | 5.71% |
| California | 2.93% | 0.23% | 2.71% |
| Northwestern | 2.74% | 0.05% | 2.69% |
| Toledo | 2.23% | 0.01% | 2.22% |
Notre Dame shot up the rankings after throttling Texas, and has stayed roughly in the same spot ever since. Ole Miss is the only team that is more ascendant. Not only did the Rebels emerge from the glut of SEC West teams* as the one that might actually be really great, but they also crossed off their biggest hurdle of the year with a win, which is something no other team can say, save for Toledo. Everyone else on this list did a good job winning all of their games, and thus, reaping the benefits. This would lead us to believe that the biggest fallers suffered a bunch of losses, right? Well, not quite:
| Team | Current Odds | Original Odds | Difference |
| Texas Christian | 26.32% | 45.65% | -19.33% |
| Oregon | 0.03% | 17.08% | -17.05% |
| Ohio State | 53.06% | 68.06% | -15.00% |
| Tennessee | 0.26% | 7.36% | -7.11% |
| North Carolina | 0.84% | 4.88% | -4.04% |
| Baylor | 45.25% | 49.05% | -3.80% |
| Virginia Tech | 0.05% | 3.54% | -3.49% |
| Arkansas | 0.00% | 2.92% | -2.92% |
| Stanford | 4.26% | 7.00% | -2.74% |
| Florida State | 12.11% | 14.74% | -2.63% |
I mean sure, there's Oregon, Tennessee, and poor, poor Arkansas on this list. But what strikes me most is that the top three teams at the start of the season have all gone undefeated, but still suffered sizable drops in their playoff probabilities. Some of this is the effect I mentioned earlier of raw probabilities catching up to reality. But we've also seen TCU and Ohio State play slightly more human football than we originally expected. What initially started as a season where a few teams were expected to dominate turned into a bit of a toss-up. There's still a good separation between the top 15 or so teams and everyone else, but in terms of the race for the four playoff spots, it's as wide open as ever.
*Fun note: Texas A&M started the season at 10.06% odds, and is now up just a tiny amount at 10.15% odds. One way or another, that number is going to change drastically in the coming weeks.
Week 5 Preview
| Home | Away | Home Win Prob | Playoff Teams Lost |
| Clemson | Notre Dame | 48.54% | 0.070 |
| Georgia | Alabama | 58.05% | 0.044 |
| Florida | Ole Miss | 24.53% | 0.037 |
| Oklahoma | West Virginia | 63.19% | 0.036 |
| Baylor | Texas Tech | 81.93% | 0.030 |
| Wisconsin | Iowa | 70.34% | 0.029 |
| Indiana | Ohio State | 8.28% | 0.015 |
| Texas A&M | Mississippi State | 73.48% | 0.011 |
| TCU | Texas | 88.58% | 0.010 |
| NC State | Louisville | 71.08% | 0.008 |
Week 5 is the first truly great week of the 2015 season. The top four games on this list have more playoff impact than any single game from Week 4. Aside from most of these games featuring legitimately great teams, you'll also notice that every team has at least an 8% chance of winning the game. The era of Baylor-Lamar showing up on this list is over.* There wasn't even room for a battle of unbeaten in a major conference, as Oklahoma State-Kansas State is relegated to the "Others Receiving Votes" category. Hell, the Pac 12 doesn't even show up on here, and it's still a conference with teams and games and such (I checked just to make sure). Should be a fun weekend.
*One other fun thing: Four of these games are Noon kickoffs. You can't nap through the early afternoon anymore. Sorry.
The Irish's coin flip in Death Valley is obviously a great tentpole for the week, but there's a billion other interesting games. West Virginia starts their horrific road slate in the place that Bob Stoops never used to lose games in. Texas Tech tries to avoid their second heartbreaking loss in as many weeks. NC State and Iowa try to keep their weird seasons going. And Alabama is facing effective playoff elimination in their once-a-decade trip to Athens. You should probably just watch football all day. Trust me on this.
