Stanford football 2015: Examining the college football playoff picture

Relax. Not Everybody Is Going Undefeated.

I've been noticing an increasing number of comments right here on Rule of Tree expressing worry: what if Stanford wins out, but doesn't reach the CFP because all the other Power Five conferences end up with an undefeated team? And it's not too surprising that this line of thinking is gaining traction; after all, every other Power Five conference still has at least one undefeated team left standing, and two conferences (the Big Ten and the Big 12), even have THREE teams undefeated!

So, let me put your mind at ease. Not everybody is going to complete the season undefeated. It's just not going to happen. Well, it's probably not going to happen anyway.

Upsets can and do happen, and it's very hard for a team to survive the entire season without picking up a loss somewhere (even if it is a ridiculously unexpected loss). Just ask last year's Ohio State team; yes, they won a national championship, but not before they put up a mind-boggling loss to Virginia Tech. Or ask last week's Florida State team; many were making noise about how they'd once again go undefeated, until they ran into Georgia Tech this past weekend. Hell, even ask this year's Stanford team that somehow found a loss to an inferior Northwestern team.

It's very difficult to go undefeated, and it's very unlikely that all four conferences will survive with an undefeated champion.

In fact, I have the probability of all four conferences ending up with an undefeated champion at a mere 0.37%. This means that there's a 99.63% that at least one conference champion finds a loss.

More about that calculation in a moment, but first:

A Word on Methodology

In order to get my win probabilities for each team, I used the S&P rankings that Bill Connelly puts out right here in SB Nation. I calculated the point spread for each team's remaining matches, made an adjustment for home-field advantage, and then compared historic point spreads (since 1996 when the new overtime rule took effect) to how often a team won; I then came up with a linear regression that converts point spreads into win probabilities.

Those are a lot of scary statistical words, but the long and the short of it is that I'm using Bill Connelly's S&P model, and using historic data to estimate home-field advantage and how often a team wins, given a certain point spread.

Got it? Okay! On to the good stuff!

Probability of an Undefeated Big Ten Champion

Right now, I have the probability of an undefeated Big Ten Champion at around 33.44%. In the East, Michigan State and Ohio State are both undefeated, but will have to play each other (so only one can end up undefeated at the end of the season). In the West, Iowa is undefeated (and plays neither Michigan State nor Ohio State, at least not until the Big Ten Championship). Let's discuss each team's probabilities in turn.

Ohio State

Vs. Minnesota	@Illinois	@Michigan St	@Michigan	B1G Champ	Undefeated %
91.45%	75.92%	72.16%	26.5%	63.97%	8.49%

Even defending national champion Ohio State only has an 8.49% of remaining undefeated heading into bowl season. The toughest part of their schedule involves playing Michigan at the Big House, but the other Michigan team (Sparty) could also cause some noise, as could the Big Ten West champion in the conference championship game.

Michigan State

@Nebraska	Vs. Maryland	Vs. Ohio State	Vs. Penn State	B1G Champ	Undefeated %
52.52%	86.67%	27.84%	69.2%	48.86%	4.28%

Michigan State pulled off the upset of Jim Harbaugh's Michigan team, but they still have a long way to go with Ohio State, @Nebraska, and a Big Ten Championship ahead of them on their schedule. Not too surprising that their probability of remaining undefeated is only at 4.28%.

Iowa

Vs. Maryland	@Indiana	Vs. Minnesota	Vs. Purdue	@Nebraska	B1G Champ	Undefeated %
90.81%	83.07%	87.17%	93.59%	70.73%	47.49%	20.67%

Iowa may not be the best team in the Big Ten (that honor goes to Ohio State), but because they've survived the tough part of their schedule and have relatively softer opponents coming up, Iowa represents the Big Ten's best chance of having an undefeated team from the conference. Altogether, Iowa is sitting at a 20.67% chance of remaining undefeated heading into bowl season.

Putting It Altogether

Of course, to crown an undefeated team, any one of the three teams (Ohio State, Michigan State, Iowa) can go undefeated. The probability of one of these teams surviving the Big Ten is 33.44%

Probability of an Undefeated SEC Champion

Compared to the Big Ten, the probability of an undefeated SEC champion is quite a bit simpler. This is because the SEC only has one team remaining undefeated: LSU. What are LSU's odds of surviving the rest of its schedule undefeated, though?

@Alabama	Vs. Arkansas	@Ole Miss	Vs. Texas A&M	SEC Champ	Undefeated %
32.43%	83.07%	48.86%	84.39%	60%	6.67%

LSU's biggest test will be the upcoming match @Alabama. Even if it survives that test, though, it still has to get through @Ole Miss and the SEC Championship.

Probability of an Undefeated ACC Champion

The ACC actually represents the best chance of an undefeated conference anywhere. Like the SEC, the probability calculation is pretty straight forward since, after Florida State's defeat last week, there is only one remaining undefeated team: Clemson. How do they fare?

@NCSU	Vs. Florida St	@Syracuse	Vs. Wake	@S. Carolina	ACC Champ	Undefeated %
83.75%	85.59%	93.59%	94.04%	94.04%	84.39%	50.07%

With a relatively soft schedule remaining (even heading into the ACC Championship), Clemson's probability of winning out is (ever-so-slightly) better than 50%.

Probability of an Undefeated Big 12 Champion

And after two straight-forward calculations from the SEC and ACC, we now have another more complex calculation as three teams (Baylor, TCU, and Oklahoma State) still sport an undefeated record. There is indeed power in numbers, and with three teams still in the running, the Big 12 is the conference that is second-most likely to have an undefeated conference champion, at a probability of about 32.72%.

How likely is each of these teams to finish the season undefeated, though?

Oklahoma State

@Texas Tech	Vs. TCU	@Iowa State	Vs. Baylor	Vs. Oklahoma	Undefeated %
67.57%	45.95%	78.05%	25.25%	40%	2.45%

Don't count on Oklahoma State remaining undefeated (the probability of which is only 2.45%) when it has to get through a number of difficult foes, including TCU, Baylor, and Oklahoma. Fortunately, it has home field advantage for each of those three matches, but should still have a tough time with them.

Baylor

@Kansas St	Vs. Oklahoma	@Oklahoma St	@TCU	Vs. Texas	Undefeated %
91.75%	70.73%	74.75%	55.92%	94.04%	25.51%

Baylor represents the Big 12's best chance of having an undefeated team (25.51%). It has a tossup @TCU, but should be a solid favorite in all other games remaining this season.

TCU

Vs. WVU	@Oklahoma St	Vs. Kansas	@Oklahoma	Vs. Baylor	Undefeated %
55.92%	54.05%	94.04%	37.97%	44.08%	4.76%

Look out, Horned Frogs. With the exception of Kansas, all of your remaining games are tossups (or worse). The Horned Frogs are only looking at a 4.76% chance of remaining undefeated.

Putting It Altogether

Undefeated B1G	Undefeated SEC	Undefeated ACC	Undefeated Big 12	ALL Undefeated %
33.45%	6.67%	50.07%	32.72%	0.37%

It's hard for any one team to remain undefeated, but when we're speculating about every single other Power Five conference remaining undefeated, then it's nigh-on-impossible (only a 0.37% probability of it actually occurring).

To me, the more interesting question isn't about what happens if all of the other conferences have an undefeated champion; the more interesting question revolves around the pecking order of the one-loss teams if some of these currently-undefeated teams do pick up a loss. Would Stanford be preferred over the other one-loss teams?

What's the Pecking Order of One Loss Teams?

I'm not going to go into an extensive analysis here, but right now, Stanford is the second-best one-loss team (second only to Alabama). But what if some of these undefeated teams finished with exactly one loss? In the eyes of the CFP panel, where would Stanford fall in the pecking order?

Of course, it's difficult to speculate without yet knowing how ugly the loss was of each currently-undefeated team, but my best guess is that we shouldn't be worried. My belief is that all of the currently-undefeated teams need to win out since their strength of schedules are so weak, and that with the exception of Alabama, a one-loss Stanford team would be preferred over any other one-loss team in the country.

So, relax Stanford fans, and just focus on winning out. The other conferences are likely to pick up a loss somewhere, and we really shouldn't be too worried about all of the other conferences somehow remaining unscathed. It's very, very unlikely.

In fact, if you see any commenters here on Rule of Tree worried that all of the other conferences may end up undefeated, just respond "0.37%" and include a link to this article.

As you just saw, the biggest obstacle to Stanford's success is NOT that all of the other teams might somehow win out, but there is a big obstacle to Stanford earning a slot in the CFP, and that's whether Stanford can win out. To read about the odds of Stanford winning out, click here to proceed to Matt Vassar's next piece on how likely Stanford is to win out.