Strength Of Schedule

Nov 26, 2021

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I've always felt like strength of schedule should be discussed ten times more than it is in college football. OK, "ten more times" is a bit much. I've always felt like strength of schedule should be discussed 2.6 times more than it is. There are only 12 games, and the teams on your schedule can be the only difference between 5-7 and 8-4.

Think about those two numbers. Actually just think of your emotions if Illinois was 6-5 right now instead of 4-7. A chance for 7 regular season wins (for the first time in 15 years) and a better bowl slot this weekend, wins at Penn State and Minnesota so you know it's not a fluke, competitive in all but two games - the future would be so incredibly bright.

Well, whatever brightness you see from the scenario I just described should be the brightness you see from this season. The only reason we're not there is because of the schedule. I'll say that again because I think you missed it. The only reason we're not basking in the glow is because we've played one of the more difficult schedules in the country so far from Game 1 to Game 11.

What started me down this road was a comment on one of my Kerby Joseph For 1st Team All American campaign tweets. The obvious question when touting a player from 4-7 Illinois for 1st Team All American: "didn't he just play in these tiny little nothing games over here on BTN while that safety from Alabama was playing big bad opponents every week?" Well, not really. If we had played Alabama's schedule, we'd be having a much better season. And Kerby would probably have better statistics.

Calm down. There's math behind it.

First we need to discuss "strength of schedule". There's a dozen different ways to go about it. Some just look at the winning percentage of the teams you've beaten and the teams you've lost to. Some look at the efficiencies of the teams you've beaten and the teams you've lost to (meaning, how many games should they have won, not how many games they did win - this eliminates fluky teams like 2018 Northwestern or 2020 Indiana). Others go deeper than any of that and take your schedule, put it up against an average college football team, and see how an average team would have performed against your opponents.

And some live in the purely theoretical. Take the stats, not the results - and those stats include things like "talent level on the team", so it's not just how the team is performing on the field - and rank the teams. Then base the strength of schedule on those teams being the good teams. Sounds odd - "wait, so USC gets a boost just because the 247 Composite says they have a strong roster and they should be good?" - but there's some decent reasoning behind it.

So any time you see a definitive statement about strength of schedule - "Iowa played the 11th-toughest schedule this year' - you can pretty much dismiss the certainty of "11th" because there's so many different ways to go about determining that number.

There are some strength-of-schedule composites out there. Meaning, take them all and combine into one list. This calculation has a team's schedule 29th, this one has them 4th, add ten of them together and they end up averaging around 12th. Here's where Illinois stacks up in those.

The site Power Ranking Guru puts together a composite power ranking from multiple "computer-generated rankings" around the web and then makes it simple. All of the "these teams are good and these teams are bad" has been worked out in those composite rankings and then they just list the teams by average opponent ranking. "Average" is tricky, of course. Texas Tech schedules a game against Florida International, they rank 128th out of 130 teams in the composite rankings, and that one game sends TTU's strength of schedule all to hell. But, as long as we acknowledge that it's just an average, I'll tell you where Illinois ranks on their list: 4th.

The math, again, is simple. They put together a composite ranking using a bunch of different 1-130 rankings and then just list your opponents. Illinois opponents so far: 9, 10, 19, 24, 29, 30, 46, 47, 69, 77, 116. Average: 43.4. That's 4th-best nationally. But this week we play #88 Northwestern. Which means the average will dip to 47.0. Which would drop us to 9th.

Still, that's one metric. Current average ranking of opponents = 4th. With an expected drop somewhere around 8-10 after the games this weekend.

Other metrics: Warren Nolan does an ELO-based strength of schedule (ELO is that chess probabilities thing) and on that metric the Illinois strength of schedule is 14th-toughest. Jeff Sagarin's ratings puts our schedule 9th-toughest. The composite Massey Ratings combine 83 different 1-130 rankings and then they separate out strength of schedule here. The Illinois SOS: 5th.

Seems like we're getting a clear picture here. 4th, 14th, 9th, 5th. All subject to drop a bit after playing Northwestern. But it's enough for me to, at the very least, say that Kerby Joseph has played plenty of "solid competition" and deserves, statistically, to be a first-team All American (which I believe he will be for PFF but possibly not for anyone else).

Let's get back to "we'd be having a parade down Green Street if we had only played an average schedule this year". And to talk about "average schedules" and "average teams", let's use the Fremeau Efficiency Index. Mostly because of all the data he makes available.

For his strength of schedule, Brian Fremeau uses the whole "expected number of losses" thing. How would an elite team perform against your schedule? Also, how would a "good" team perform against your schedule. And finally, how would the average college football team perform against your schedule? For this exercise, since I don't really care how Georgia would have done against our schedule - let's use the average college football team.

On his ratings, he says that the average college football team would have 6.74 losses against our schedule. That's the 6th-most difficult schedule in the nation (using that metric). And it kind of "holds up", I guess. We're a decently average team (hurray!). We're 4-7 against this schedule. An average team would be 4.26-6.74 against this schedule. Checks out.

(Note - I sent Fremeau a DM about this next part, asking if this assumption was correct. I haven't heard back. I will update this if I do.)

On Fremeau's list, Illinois is 67th out of 130 teams. So almost right in the middle. He does the positive/negative thing just like Bill Connelly (breaking point is right around the middle), and Illinois is 0.04 in his overall FEI rating. Utah State (71st) is the first in the negative numbers at -0.01. Georgia is first at 1.61; Akron is last at -1.32.

So it seems to me that this should be pretty easy. Illinois is nearly the exact "average" team he's using for his calculation. So we can just look at all of those schedules and say "here's what Illinois would have done with their schedule". (Again, I'm guessing he'll DM me back and say that the math doesn't really work like that, but I'll have some fun with it until he does.)

For this exercise I'm mostly going to just round up and round down once we cross 0.5. So if an "average" team should have 3.49 losses, I'm calling that three losses. If it should have 3.51 losses, I'm calling that four. Let's jump around the entire list and have some sweet dreams.

  • Let's start with #1. If Illinois had Georgia's schedule (5.97, 33rd), we'd be 5-6 and playing Northwestern to get to six wins. I know you're probably going to struggle to adjust to this, but that's the math here. If Illinois had played Clemson, UAB, South Carolina, Vanderbilt, Arkansas, Auburn, Kentucky, Florida, Missouri, Tennessee, and Charleston Southern, the math says we (the average team) would have 5.97 losses. 5-6 going into the final week. Instead, we played our schedule (6.74), and we're 4-7.
  • Let's go with one of those Group Of Five schedules next. And let's use the MAC team in the state. Northern Illinois is 110th on the list with a 3.88. So against NIU's schedule, we'd be 7-4 and looking for our eighth win.
  • What about a team we beat like Charlotte? What if we had their schedule? Well, their number is 3.34, so we'd likely be 8-3 looking for our 9th win.
  • You can't really get to 8 losses, by the way. The hardest schedule is Indiana (who scheduled Cincinnati plus a game at Western Kentucky for some reason, all while playing in the Big Ten East), and that number is 7.08. So we'd still be 4-7.
  • Speaking of Cincinnati, 4.13 (100th). We'd be 7-4 looking for our 8th win.
  • Michigan? They're 5.52. So that's pretty much right in the middle between 5-6 and 6-5 going into this Northwestern game. We'd be looking for either win number 6 or win number 7.
  • Pitt is the one that sticks out the most. They're having this great season. 9-2 and ranked 20th. Against their exact schedule, the average team (us!) would be expected to be 6.41-4.59 right now. So we'd either be 6-5 or 7-4 going into this weekend.

I'm going to think about that last one a lot the next few days. Change nothing about this team. Still the same offense that struggles like it does. Same players, same schemes, same everything. All you do is swap schedules with Pitt. And we're either 6-5 or 7-4 going into this Northwestern game. Possibly looking for win #8!

This is why I'm always so surly when people discuss college football in "it's 95% good coaches with good schemes" terms. They'll see that Coastal Carolina's offense is 14th nationally (or whatever) and say "if Coastal Carolina can do it with marginal recruits, why can't we have an offense like that at Illinois?". Just spitballin' here, but I think it might be because the top six defenses that Illinois has faced rank 3rd, 4th, 6th, 11th, 26th, and 30th while the top six defenses Coastal Carolina has faced rank 22nd (Appalachian State), 64th, 87th, 104th, 108th, and 112th. (The other five: 121, 122, 127, and 128 plus 4-7 FCS The Citadel.)

It's something that drives me nuts about college football in general, really. I see Coastal Carolina ranked even though they lost to the only decent opponent they played (App State). Well, they were ranked until they lost to Georgia State on November 13th. But still, ranked in the top-25. Like, people are voting on the top-25 teams in all of college football and saying "I believe that Coastal Carolina is one of those 25 teams because they are 8-1". Since I'm using FEI for all of this, here's the overall FEI ranking for Coastal's entire schedule (and keep in mind that this is a ranking out of 130 FBS teams):

FCS Citadel (no ranking, but they're 4-7 in the FCS so likely the worst opponent Coastal faced)
Kansas (124)
Buffalo (112)
UMass (129)
Louisiana-Monroe (114)
Arkansas State (117)
Appalachian State (28) - this was their first loss and they fell from 15th to 24th (still ranked!).
Troy (108)
Georgia State (110)
Georgia Southern (87) - this was their second loss and they fell out of the rankings
Texas State (116)

Can you imagine something like this in any other sport? Coastal Carolina beats 4-7 FCS Citadel and then teams ranked (out of 130) 108, 110, 112, 114, 116, 117, 124, and 129 and people think they're one of the 25-best teams in that sport.

Wait, that's not even the best way to say this.

A team beats FCS Citadel. Then they beat teams ranked 124, 112, 129, 114, and 117. This tells everyone that they're the 15th-best team in the country (what?) according to the rankings in early October. They lose to the only real opponent they faced (Appalachian State) and then... stay in the rankings at #24 (what is happening?) in the next AP poll. They then beat teams ranked 108 and 110 (moving up to #22) before playing a real tough opponent ranked 87th who beats them 42-40. They're now 8-2, their best win is #108 Troy (who fired their coach this week, by the way), and they still get 28 points in the next AP Poll. Nobody is even trying at this point.

Can you imagine this happening in any other sport? Baseball combines AA, AAA, and MLB to form one big league (I know, they're affiliates - let me have this). There's a few "non-conference" crossover games but for the most part AA plays AA and AAA plays AAA and MLB plays MLB. The Akron Rubber Ducks win their division and finish with 93 wins. They even won a weekend crossover series against an MLB team! It was the Orioles, but still, they took two of three. And 93 wins!

The AP puts out a poll of the top-25 baseball teams, and there's the Rubber Ducks at #21, one spot ahead of the Mets. The reason given? "Well, the Mets only won 77 games and the Rubber Ducks won 93! When we adjust for strength of schedule that still means the Rubber Ducks are better than the Mets." You try to say "right but if the Mets had played Akron's schedule they would have won 120 games" and everyone shouts you down.

That's what bothers me about college football and strength of schedule. People think they're adjusting for it, but they're not. "Coastal Carolina could be a top-10 team since they're 9-2, but adjusting for strength of schedule, they're more like the 21st-best team." No, they're maybe the 50th-best team. Good on them for going 9-2, but let's be honest here, they'd be 3-8 right now in the SEC.

Let's bring all of this back to Illinois football. Your Tony Petersen opinions: you have to apply this. Your thoughts on Pitt being 9-2: you have to apply this. Illinois being 6-5 with a chance of getting to 7 wins had we played Oklahoma's schedule this year: you have to accept it.

Look, there's no way to "know" these things. We failed late against Purdue and Maryland and maybe that would have meant we would have failed late against the teams on Oklahoma's schedule. I get that we're dealing with the theoretical here.

But I still don't know why this is something that people seem to minimize. The Coastal Carolina offense would not be 14th nationally if placed in the Big Ten. Coastal does not deserve a single vote in any poll when they don't have a single win over any team above the 20th percentile of FBS football. The difference in difficulty between their schedule and Illinois' schedule is probably twice what you think it is. Maybe three times. 2.6.

One last thing. I'll answer a question you might be wanting to ask. Isn't the Illinois football schedule always "difficult"? The Big Ten is always tough. Is this season uniquely hard or something? In a word, yes.

Let's use the same "average losses" stat from the FEI over the last 10 seasons. How an average team would do against our schedule (ranked among the other 130 teams):

2012: 48th
2013: 59th
2014: 34th
2015: 59th
2016: 47th
2017: 49th
2018: 62nd
2019: 55th
2020: 57th
2021: 6th

No, it's not just because UTSA is 11-0. 2012 had 9-3 Louisiana Tech and 2016 had 12-0 Western Michigan. No, it's not simply because the required Power Five non-conference opponent is now Virginia instead of UConn or South Florida. It's a combination of many things, with a big one being resurgent seasons from Purdue, Rutgers, and others meaning there were really no weeks off during the Big Ten portion of the schedule. Even the "bad" teams (3-8 Nebraska) were statistically improved.

And I'm fairly bitter about it, to be honest. Any of those schedules from 2012 to 2019 and I'm almost certain we're already bowl eligible and looking to improve that bowl slot this weekend.

Yes, even with this exact same offense.


Brave Illini on November 26, 2021 @ 12:53 PM

I thought Michigan State had a soft schedule before their game against Michigan. Apparently their AD and Trustees don't consider SOS much either.

Bear8287 on November 26, 2021 @ 07:57 PM

Even the "bad" teams (3-8 Nebraska) were statistically improved.

“bad” Nebraska is PF: 239 & PA: 239 in the B1G and are 1-8 for their efforts…

Shemp89 on November 26, 2021 @ 09:28 PM

With you 100% on this topic, Robert. My favorite all-time series of yours was many years ago when you put Northwestern's SOS against ours, heads-up. All the early-period Fitz love nationally based on wins over cupcakes, while RG was scheduling tough non-conference opponents, for...some reason.

CKWatt on November 28, 2021 @ 07:30 PM

I would love to read this. Any idea what it was called or when it was published so I can look for it in the archive here?

Dan Allen on November 27, 2021 @ 07:33 AM

Really interesting stuff here, Robert. Glad to see my gut feeling that we are facing an exponentially tougher schedule this season actually has some data to support it.

ItsTBaggins on November 30, 2021 @ 02:50 PM

ItsTBaggins on November 30, 2021 @ 02:51 PM


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