clock menu more-arrow no yes

The 2018 advanced college football stats glossary

New, 1 comment

Here is a glossary for the terms used in the 2018 college football season previews at SB Nation.

247 Composite Ratings

247Sports catalogues both its own recruiting ratings and a composite rating compiled from a few different recruiting services. The Composite rating has proven to be the most reliable from a projections standpoint, so that is what I use in the annual preview series.

I am sharing the actual decimal rating instead of the star rating, but the gist is that anyone above a 0.8950 is a four- or five-star, anyone above 0.7950 is a three-star, etc. It is set up so that a four-star rating is an A grade, three-star is a B grade, etc. (Think of five-star ratings as an A+.)

Adj. Line Yards

An opponent-adjusted version of the line measure derived from the formula found here. The idea is to divvy credit for a given rush between both the runner and the blockers.

Adj. Pace

This takes into account both a team’s tempo (in terms of seconds per play) and the type of plays it runs. Since passes, on average, take up less time (thanks to the fact that 30-50 percent of them are incomplete and stop the clock), pass-heavy offenses are prone to run more plays, therefore limiting the effectiveness of a general plays-per-game measure. Adj. Pace takes a team’s run-pass ratio into account.

Adj. Points and Scoring Margin

Used in the team stat profiles, this is a look at how a team would have performed in a given week if playing a perfectly average team, with a somewhat average number of breaks and turnovers. It takes into account the factors that go into winning a given game (not simply the end result) and adjusts for the quality of opponent.

Adj. Sack Rate

An opponent-adjusted measure of sack rates.

Adj. TO Margin

What a team’s turnover margin would have been if it had recovered exactly 50 percent of all the fumbles that occurred in its games, and if the INTs-to-PDs for both teams was equal to the national average, which is generally around 21-22 percent.

If there is a huge difference between TO Margin and Adj. TO Margin (in other words, if fumbles, dropped interceptions, or other lucky/unlucky bounces were the main source of a good/bad TO margin), that suggests that a team’s luck was particularly good or bad and might even out either in the next season or in the rest of the current one.

Avg. FP

See the Five Factors section.

F/+

The official college football ratings of record at Football Outsiders. F/+ is a combination of the Brian Fremeau’s Fremeau Efficiency Index (FEI) and my S&P+.

FIVE FACTORS

The Five Factors are the basis for my S&P+ ratings. They stem from the work done in this post.

Over time, I’ve come to realize that the sport comes down to five basic things, four of which you can mostly control. You make more big plays than your opponent, you stay on schedule, you tilt the field, you finish drives, and you fall on the ball. Explosiveness, efficiency, field position, finishing drives, and turnovers are the five factors to winning football games.

  • If you win the explosiveness battle (using PPP), you win 86 percent of the time.
  • If you win the efficiency battle (using Success Rate), you win 83 percent of the time.
  • If you win the drive-finishing battle (using points per trip inside the 40), you win 75 percent of the time.
  • If you win the field position battle (using average starting field position), you win 72 percent of the time.
  • If you win the turnover battle (using turnover margin), you win 73 percent of the time.

This is from 2013 college football game data. It’s very, very similar from year to year.

These are good odds. And they speak to the fundamentals of football itself. You want to be efficient when you’ve got the ball, because if you fall behind schedule and into passing downs, you’re far less likely to make a good play. You want to eat up chunks of yardage with big plays, because big plays mean both points and fewer opportunities to make mistakes. When you get the opportunity to score, you want to score. And when you give the ball back to your opponent, you want to give them to have to go as far as possible.

I reference the Five Factors in a number of different ways in my previews and stat profiles, some adjusted for opponent, some not. They are all interrelated.

  1. Efficiency. Presented through success rate (unadjusted, see definition below), Success Rate+ (adjusted), and Marginal Efficiency (see entry below). As defined above, success rates examine your efficiency and consistency in staying on schedule and putting yourself in position to move the chains. In terms of projection, it is by far the most important of the factors.
  2. Explosiveness. Presented through Isolated Points Per Play (IsoPPP, which is unadjusted), IsoPPP+ (adjusted), and Marginal Explosiveness (see entry below). IsoPPP is the Equivalent Points Per Play (PPP) average on only successful plays. This allows us to look at offense in two steps: How consistently successful were you, and when you were successful, how potent were you? Big plays often make the difference in a given game, but they are random enough to be unreliable.
  3. Field Position. Presented through average starting field position (unadjusted) and FP+ (adjusted). This is mostly self-explanatory, with one important note: You should remember to measure an offense by its defense’s starting field position, and vice versa. Special teams obviously play a large role in field position, but so do the effectiveness of your offense and defense. So in the team profiles, you’ll find Defensive Starting FP in the offensive section and Offensive Starting FP in the defensive section.
  4. Finishing Drives. Presented through points per trip inside the opponent’s 40 (unadjusted) and Red Zone S&P+ (adjusted). Also mostly self-explanatory. These measures look not at how frequently you create scoring opportunities, but how you finish the ones you create. And yes, for the purposes of these stats, the “red zone” starts at the 40, not the 20.
  5. Turnovers. Using both Turnover Margin and Adjusted Turnover Margin (as defined above), we can take a look at both how many turnovers you should have committed (on offense) or forced (on defense) and how many you actually did. This tells us a little bit about quality and a lot about the Turnovers Luck idea defined above.

FP+

See the Five Factors section.

Fremeau Efficiency Index (FEI)

FEI considers each of the nearly 20,000 possessions every season in major college football. All drives are filtered to eliminate first-half clock-kills and end-of-game garbage drives and scores. A scoring rate analysis of the remaining possessions then determines the baseline possession efficiency expectations against which each team is measured. A team is rewarded for playing well against good teams, win or lose, and is punished more severely for playing poorly against bad teams than it is rewarded for playing well against bad teams. For more, go here.

Havoc

The percentage of plays in which a defense either recorded a tackle for loss, forced a fumble, or defensed a pass (intercepted or broken up). If QB hurries were a reliable stat (at the college level, there is far too much inconsistency in how they are recorded), they would be included here, too.

In the team stat profiles, Havoc Rate is both presented as an overall measure and broken out into unit-specific defensive line, linebacker, and defensive back measures.

Highlight Yards

This is the portion of a given run that is credited only to the running back; after a certain number of yards, the line has done its job, and most of the rest of the run will be determined by the running back himself.

For more information, start here. An important note: a player’s per-carry highlight yardage is calculated as follows: Highlight Yards divided by Opportunities. In this case, Opportunities mean only the carries in which the offensive line “did its job,” i.e. carries that went at least five yards. With a different denominator, then, it is possible for a player’s Highlight Yards per carry to be much higher than his overall yards per carry.

IsoPPP

See the Five Factors section.

Marginal Efficiency

A new toy for 2018, the idea behind marginal efficiency and marginal explosiveness is simple: what if we adjust our basic efficiency (success rate) and explosiveness (IsoPPP) measures for down, distance, and field position? Those factors create a baseline, and comparing a unit’s or player’s output to the baseline gives you a positive or negative number. More here:

Marginal Efficiency: the difference between a player’s success rate* (passing, rushing, or receiving) or success rate allowed (for an individual defender) and the expected success rate of each play based on down, distance, and yard line.

Marginal Explosiveness: the difference between a player’s IsoPPP** (passing, rushing, or receiving) or IsoPPP allowed (for an individual defender) and the expected IsoPPP value of each play based on down, distance, and yard line.

For offensive players, the larger the positive value, the better. For defensive players, it’s the opposite — the more negative, the better.

Marginal Explosiveness

See Marginal Efficiency.

Opportunity Rate

This is the percentage of carries in which the offensive line “does its job” and produces at least five yards of rushing for the runner. (Generally speaking, the first five yards are considered the line’s responsibility, the next five are split evenly between the runner and the line, and anything over 10 yards is all on the runner.) See Highlight Yards and Adj. Line Yards for more information.

Passing Downs

Second-and-8 or more, third-and-5 or more, or fourth-and-5 or more. These are downs in which passing is easily the most likely option for gaining the necessary yardage, and defenses hold the upper hand. Offenses typically throw about two-thirds of the time on passing downs.

PD-to-INC

A defensive personality stat, this looks at the percentage of an opponent’s incomplete passes that you either intercepted or broke up. This isn’t necessarily a quality stat, just a look at general aggressiveness levels.

Percentile Performances

This basically amounts to a single-game S&P+ performance evaluation — it takes the factors that go into S&P+ (overall, offense, and defense), adjusts for opponent, and slaps it onto the bell curve.

You’ll see referencing “average percentile performance” as a way for me to talk about teams’ previous performances. Because of everyone’s history with standardized tests, this is hopefully a pretty easy concept to understand and communicate.

Points Per Trip inside the 40

See the Five Factors section.

Postgame Win Expectancy

Presented in the team stat profiles, this makes the following statement: “Based on the key stats from this game — success rate, big plays, field position components, turnovers, etc. — you could have expected to win it X percent of the time.” Luck and randomness play a major role in the game of football, and this is an attempt to look at just how random a given outcome may have been.

Note: This measure has nothing to do with pre-game projections or opponent adjustments, only the postgame stats from a specific game.

Power Success Rate

As used in Football Outsiders’ pro line stats, this is the percentage of runs on third or fourth down, two yards or less to go, that achieved a first down or touchdown. Also includes runs on first-and-goal or second-and-goal from the two-yard line or closer.

Red Zone S&P+

See the Five Factors section.

S&P+

A college football ratings system designed by me and derived from the play-by-play and drive data of all 800+ of a season’s FBS college football games (and 140,000+ plays). For more, go here. It is presented as an adjusted scoring average.

Second-order wins

Using Postgame Win Expectancy numbers for the entire season, you get a pretty good idea for how many games a team could have expected to win. As I mentioned here, “[second-order wins] basically say that playing the way you did, against the opponents you played, you would usually end up with a record of X, and it compares it to your actual record, Y. If one is too far from the other, you’re probably going to see some regression (or progression, as the case may be) to the mean.”

In the short-term, you can use second-order wins to gauge who may have been on the fortunate or unfortunate side of randomness for a given month, season, etc. Over the long-term, it can potentially be used to gauge perpetually underachieving or overachieving coaches.

Special teams efficiency

Since 2016, I have worked special teams values into the S&P+ formulas. Here are the basics:

  • Field Goal Efficiency: Based on the length of a given field goal, we create an expected success rate, then multiply it by three points to create an expected point value. Field Goal efficiency compares your team’s output from field goals to the expected value, then divides it by the number of kicks. It is the only of the special teams measures that don’t take the form of a success rate.
  • Kickoff Efficiency: On average, kickoffs net around 40-41 yards. Since touchbacks are a 40-yard net, kickoff efficiency is simply the percentage of your kickoffs that net at least 40 yards.
  • Kick Return Efficiency: The percentage of kick returns (not including touchbacks or fair catches) that result in an unsuccessful kickoff for the kicking team.
  • Punt Efficiency: Based on where the punt takes place, we create an expected net punting value. Punt efficiency is simply the percentage of your punts that resulted in a net higher than the expected value.
  • Punt Return Efficiency: The percentage of punt returns (not including touchbacks or fair catches) that result in an unsuccessful punt for the punting team.
  • Special Teams S&P+: Each of the above measures gets slapped onto a bell curve and is given a weight based on its predictiveness (field goal efficiency has the highest level of predictiveness, punt returns the lowest). That becomes a Special Teams S&P+ rating.

Standard Downs

First downs, second-and-7 or fewer, third-and-4 or fewer, and fourth-and-4 or fewer. These are the downs in which the offense could conceivably either run or pass and therefore has an overall advantage over the defense. Offenses typically run about 60 percent of the time on standard downs.

Stuff Rate

This is the percentage of runs where the runner is tackled at or behind the line of scrimmage. Since being stuffed is bad, offenses are ranked from stuffed least often (No. 1) to most often (No. 125); for defenses, the opposite is true.

Success Rate

A common Football Outsiders tool used to measure efficiency by determining whether every play of a given game was successful or not. The terms of success in college football: 50 percent of necessary yardage on first down, 70 percent on second down, and 100 percent on third and fourth down.

Success Rate+

An opponent-adjusted version of Success Rate. As with most other “+” measures, it is built around a baseline of 100.0. Anything over 100.0 is better than average, anything below 100.0 is worse than average.

Turnovers Luck

Presented in Points Per Game fashion, Turnovers Luck looks at the difference between a team’s Turnover and Adj. TO Margins and, using the average point value of a turnover (~5.0 points), projects how many points a team gained or lost per game last season.