Predicting the national championship game using SPM comps

The LSU Tigers are currently 5.5-point favorites to beat the Clemson Tigers in Monday night’s national championship game. Honestly, if I went with my gut yesterday, I would have picked LSU to cover that spread without hesitation. I’ve watched them play. I’ve consistently underappreciated how prolific that offense is and misjudged how badly they’d beat good teams with good defenses. LSU to cover, probably big, amirite?

So I was surprised when I fired up the SPM this morning and it spit out a tie game. My first inclination was that something had gone wrong and that I was going to have to scrap the idea of doing an SPM National Championship preview post because I didn’t trust the results myself.

But looking at the details of why the SPM came to that conclusion — along with its performance over the course of the bowl season — made me re-think things. With one game left to play, the SPM is 25-15 (62.5%) for bowl season. We value Bill Connelly’s SP+ predictions as the gold standard we measure against around here, and even that is only 18-22 (45%) for bowl season. So I figured it’s worth taking a look at why the SPM doesn’t think LSU is a clear favorite Monday night against Clemson, and then we can all decide for ourselves whether or not to listen.

LSU Tigers vs. Clemson Tigers

From the perspective of LSU

LSU’s points:

  • LSU scoring offense for the season: 48.9
  • Clemson scoring defense for the season: 11.5

The Clemson scoring defense is most similar to the following prior LSU opponent(s) (FBS only):

  • Georgia 12.6
  • Florida 15.5

LSU had no trouble against the Gators, scoring 42 points despite the fact that Florida allowed an average of only 12.6 points all season. The same is true with respect to Georgia: LSU scored 37 on the Bulldogs. When LSU plays a team with a defense like Clemson’s, its offense scores almost three times as many points as those teams usually give up. It’s not unreasonable to think that LSU can score 30 points against a really good Clemson defense. The SPM predicts 32.2 points for LSU.

Clemson’s points:

  • LSU scoring defense for the season: 21.6
  • Clemson scoring offense for the season: 45.3

The Clemson scoring offense is most similar to the following prior LSU opponent(s):

  • Alabama 47.2
  • Oklahoma 42.1

LSU couldn’t stop Alabama, which got 41 points against them, but they did pretty well against Oklahoma, which they held to only 28. Those are two quite different results against similar offenses. Taken together, it’s 77% of what those teams usually get; Oklahoma alone got only 67% of what it usually gets. That would make it 30-35 points for Clemson against LSU. The SPM puts it at 34.9 points for Clemson against LSU.

Estimated score: Clemson 34.9, LSU 32.2

From the perspective of Clemson

Clemson’s points:

  • Clemson scoring offense for the season: 45.3
  • LSU scoring defense for the season: 21.6

The LSU scoring defense is most similar to the following prior Clemson opponent(s) (FBS only):

  • Texas A&M 22.5
  • North Carolina 23.7

Clemson scored 21 points against North Carolina and 24 points against Texas A&M. Basically, when the Clemson offense goes up against a defense like LSU’s, they generally get about what those teams usually give up. The SPM says that’s 21 points for Clemson against LSU.

LSU’s points:

  • Clemson scoring defense for the season: 11.5
  • LSU scoring offense for the season: 48.9

The LSU scoring offense is most similar to the following prior Clemson opponent(s):

  • Ohio State 46.9
  • Louisville 33.1

That Louisville comp is not especially helpful, but the Ohio State comp is. The Buckeyes got only 23 points against Clemson’s defense (49% of what they usually score). If that’s indicative, Clemson might just be able to hold LSU to half its usual point total, or 24 points. Because it includes the Louisville comp, the SPM says 21 points for LSU against Clemson, but I’m going to override it and call it 24.

Estimated score: LSU 24, Clemson 21

SPM Final Estimates

Throw it in, cook it up, take a peek:

SPM Final estimated score: LSU 28.1, Clemson 28

SPM Final estimated spread: LSU -.1

Difference between the SPM and the current spread: 5.4

Eyeball adjustments

As I said in the opening paragraph, my gut pick is LSU to cover and probably to cover comfortably. But after looking at those numbers, “comfortably” is off the table for me and even covering is in question. If I had to make a pick, I’d say LSU does not cover, and I would no longer be surprised if Clemson won outright.

So, my eyeball-adjusted prediction is LSU 31, Clemson 28.

Other predictions from other systems

As I said before, LSU is a 5.5-point favorite. With an over/under of 68.5 to 69.5, that translates to something like LSU 37, Clemson 32.

I have not yet seen Connelly’s SP+ prediction, but I’ll update once it’s available.

ESPN’s FPI gives . . . Clemson a 55.8% chance of winning.

Bottom line

The SPM thinks this is basically a pick ’em, so it does not like LSU to cover the 5.5-point spread. My gut — which likes LSU to cover comfortably — has been reined in by the machine, so I now like LSU to win, but only barely.

  • Vegas: LSU -5.5 (~LSU 37, Clemson 32)
  • SP+: TBD
  • SPM: LSU 28.1, Clemson 28 (LSU doesn’t cover)
  • Me: LSU 31, Clemson 28 (LSU doesn’t cover)
  • FPI: Clemson, 55.8% chance of winning

What do y’all think?

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