SP+ and Adjusted Efficiency: How Advanced College Football Ratings Work

If you follow college football for more than a week, someone will tell you a team is "better than its record" because of SP+. It's one of the most cited advanced ratings in the sport — and one of the most misunderstood. So let's build the idea from the ground up, without the mystique. By the end you'll know what SP+ measures, why it adjusts for opponents, and where it can lead you astray.

The one-sentence version: SP+ estimates how many points better or worse than average a team is, after accounting for who it played. Everything else is detail.

Why raw stats lie

Imagine two offenses that both average 6.5 yards per play. One did it against the toughest defenses in the country; the other padded its numbers against a soft non-conference slate. Their raw stats are identical, but they are not equally good. Raw, unadjusted numbers reward the team with the easier schedule. Every serious rating system exists to undo that distortion.

The fix is opponent adjustment: judge each performance relative to what a typical team does against that same opponent. Beat a great defense by a little, and you get credit. Beat a bad one by a little, and you don't.

A simple opponent adjustment, with real data

You don't need SP+'s machinery to see the principle work. Take every FBS team's average scoring margin in 2024, then add the average margin of the teams it played — one round of adjustment for schedule. Here's the top of that list, computed from public results (the script is in /scripts):

Notice what adjustment does to the bottom of the picture, too. Indiana went 11-1 and posted the third-best raw margin in the country (+18.2) — but its adjusted margin falls to about eleventh, because it played one of the softest schedules in major college football. That's not an insult to a great season; it's the entire point. SP+ does this same thing, far more rigorously.

What SP+ actually combines

SP+, developed by Bill Connelly, is built on a few ingredients:

• Efficiency — success on a play-by-play basis (see our success rate and EPA explainer), not raw yards.
• Explosiveness — the value of the big plays a team produces and allows.
• Field position and finishing drives — where drives start and whether they end in points.
• Opponent adjustment — all of the above, recalibrated for schedule strength.

The output is split into an offensive rating, a defensive rating, and a combined number expressed in points. A team with a +25 SP+ rating is, in expectation, about 25 points better than a perfectly average team on a neutral field. It is tempo-free by construction: because it works in per-play and per-drive terms, a fast, high-snap offense isn't flattered just for running more plays.

The live ratings table

Where SP+ misleads

SP+ is a model, not gospel. A few honest caveats:

• Early season noise. With only a game or two played, the rating leans heavily on preseason projections. Don't over-read September.
• It's descriptive and predictive, not a result. SP+ can rate a team that lost higher than one that won. That's a feature — it's measuring quality, not counting trophies — but it's not how championships are decided.
• Injuries and personnel changes aren't fully captured. A rating built on ten games doesn't know your quarterback just got hurt.
• Garbage time can leak in. Good systems down-weight it, but no adjustment is perfect.

Use SP+ the way you'd use any good instrument: as a sharper lens, not a verdict. It tells you, far better than the standings do, who has actually played well against whom. Pair it with your own eyes and you'll be right more often than the loudest person in the group chat.