The Simple Rating System: Bringing order (kinda) to chaos

[Ed. Note: This is the first post by my good friend and stat guru Chase Stuart. For at least the rest of this season, Chase will be contributing his unique perspective to the site. Chase has previously contributed to the New York Times Fifth Down and the Pro-Football Reference Blog. You can also follow Chase on twitter.]

The last two seasons, I have published college football ratings using the Simple Rating System. Before explaining how the Simple Rating System (SRS) works, allow me to first explain what the SRS is trying to do (and just as importantly, what it’s not trying to do).

A want and enjoyment of numerosity

Most rating systems fall into one of two categories. A rating system could simply replicate the standings in any particular league; such a rating system would best be described as retrodoctive or explanatory. A retrodictive rating system fits the data to explain what happened in the past. The BCS computer ratings are mostly retrodictive; so are player or team ratings that give significant weight to high-leverage plays that tend to be highly random (clutch play, fumble recovery rates, etc.). An explanatory rating system tries to measure how much a team or player has accomplished in the past; it does not attempt to answer the question “what will happen next?” When Bill Parcells said “You are what your record says you are,” he’s championing retrodictive ratings. So was Rich Kotite when, coaching the 7-2 Eagles in 1994, he said to the media: “Judge me by my record.” An explanatory rating system would say that Kotite and his Eagles were doing well; but it would never have predicted that Kotite would go 4-35 over the next — and final — 39 games of his career.

The other type of rating system is a predictive system, which works as they name implies: it tries to predict the future. Here is a useful chart detailing some of the differences between the two in college football rating systems. Predictive rating systems are not very concerned with wins and losses; instead, they focus on more granular pieces of data. The best and most obvious example of a predictive rating system would be the formulas used by the folks in Vegas. Those who make point spreads aren’t disturbed if their rankings place Team A, which has “accomplished less” than Team B, higher up in their rankings. This weekend produced a useful example. No purely retrodictive rating system would put the Oklahoma Sooners ahead of the Kansas State Wildcats. Oklahoma was 6-1 but lost to a mediocre Texas Tech team; Kansas State was undefeated and had beaten some solid teams, albeit in less than thrilling fashion. Both the BCS ratings and the Associated Press’ rankings had Kansas State over Oklahoma, because those systems are designed to acknowledge accomplishments. But despite being the higher ranked team and playing at home, Kansas State was a 14-point underdog to the Sooners. And Oklahoma promptly went into Manhattan and blew out the Wildcats, 58-17.

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ESPN’s new Total Quarterback Rating

The NFL’s quarterback rating is bizarre and misleading, so it is no surprise that many have tried to invent the better mousetrap. What is a bit surprising is that ESPN has invented its own metric, which it will undoubtedly promote relentlessly. And, in the twist that is maybe what is most surprising of all, it’s actually pretty good, or at least a well grounded attempt to move the ball forward (at least when it comes to this kind of thing). As Chase explains:

The [formula behind the existing] quarterback rating is complicated, but it can be reduced to a simple formula. That’s what Bob Carroll, Pete Palmer and John Thorn discovered in their groundbreaking book, The Hidden Game of Football. Essentially, QB rating is equivalent to yards per attempt, but with a 20-yard-bonus for each completion, an 80-yard-bonus for each touchdown, and a 100-yard-penalty for an interception. Such adjustments should seem ridiculous to every reader, which is why everyone finds quarterback rating ridiculous. By way of comparison, PFR’s ANY/A formula — in addition to including relevant data on sacks — gives no bonus for completions, a 20-yard bonus for touchdowns and a 45-yard penalty for interceptions.

But on Thursday, ESPN released the methodology behind its new QB Rating. And last night, ESPN aired an hour-long segment at 8 PM to discuss the new formula. So how does ESPN’s formula look? There’s some good and some bad, which means it has exceeded my expectation. . . .
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Things that are self-recommending – football statistics edition

Bill Connelly — the college football expert for Football Outsiders — has a new SBN Blog, Football Study Hall; such a fact is high on the list of self-recommending things. The idea for the site is to provide a one-stop shop for advanced stats for college football, with a bit more of a fan-flavor than some of the other “stat heavy” sites out there. And Bill’s already got some good stuff up:

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.

The idea behind Success Rate is simple: every play is deemed successful or unsuccessful based on down, distance and yardage gained. Plays on first, second and third downs (and fourth, for that matter) all have as close to the same success rate as possible (between 40% and 45%).

To see what Success Rate tells us, exactly, let’s have a look at it in action. Two notes before moving forward:

1. Any reference to Success Rates as it pertains to rankings eliminates garbage time plays. Rankings are derived from plays that took place while the game was “close”: within 28 points in the first quarter, 24 in the second, 21 in the third, or 16 in the fourth.

2. As a frame of reference, the average success rate for FBS teams from 2005-10 was 41.6%. . . .

Ten Best Single-Season Success Rates, 2005-10
1. Hawaii (2006): 60.8%
2. Texas Tech (2008): 56.1%
3. Wisconsin (2010): 55.3%
4. Oklahoma (2008): 55.2%
5. Florida (2007): 55.0%
6. BYU (2008): 54.8%
7. Missouri (2008): 54.7%
8. USC (2005): 54.1%
9. Boise State (2010): 54.0%
10. Texas (2008): 54.0%

One of my favorite things about college football is how there are so many different ways to move the chains. Seeing a team like Wisconsin or Navy on the list above would be no surprise — they’re the prototypical grind-it-out, three-yards-and-a-cloud-of-dust teams. But while Wisconsin locked down the three-spot, a run-and-shoot offense took the top ranking, while spread teams filled out most of the Top 10. Invention in college football derives from trying to find different ways to gain five yards, and in college football, there are many, many different ways.

(Speaking of invention … it really is incredible to see just how far ahead of the curve the Big 12 was when it came to the spread. Of the top ten teams above, four were from the 2008 Big 12 alone. That was truly the perfect confluence of innovation and skill position experience.)

Call it the Mike Leach effect, but he’s right that: other than a few other elite offenses and talent laden Florida and USC squads, the Big 12 had the brightest offenses of the decade. In any event, head over to Bill’s new spot.

Bidding for the kickoff

A system for bidding for the kick-off:

Dispensing with a coin toss, the teams would bid on where the ball is kicked from by the kicking team. In the NFL, it’s now the 30-yard line. Under Brams and Jorasch’s rule, the kicking team would be the team that bids the lower number, because it is willing to put itself at a disadvantage by kicking from farther back. However, it would not kick from the number it bids, but from the average of the two bids.

To illustrate, assume team A bids to kick from the 38-yard line, while team B bids its 32-yard line. Team B would win the bidding and, therefore, be designated as the kick-off team. But B wouldn’t kick from 32, but instead from the average of 38 and 32–its 35-yard line.

This is better for B by 3 yards than the 32-yard line that it proposed, because it’s closer to the end zone it is kicking towards. It’s also better for A by 3 yards to have B kick from the 35-yard line, rather than from the 38-yard line, it proposed if it were the kick-off team.

In other words, the 35-yard line is a win-win solution–both teams gain a 3-yard advantage over what they reported would make them indifferent between kicking and receiving. While bidding to determine the yard line from which a ball is kicked has been proposed before, the win-win feature of using the average of the bids–and recognizing that both teams benefit if the low bidder is the kicking team–has not. Teams seeking to merely get the ball first would be discouraged from bidding too high–for example, the 45-yard line–as this could result in a kick-off pinning them far back in their own territory.

“Metaphorically speaking, the bidding system levels the playing field,” Brams and Jorasch maintain. “It also enhances the importance of the strategic choices that the teams make, rather than leaving to chance which team gets a boost in the overtime period.”

This has been proposed before and I think it’d work well. It would also provide more opportunities to second guess coaches — a favored activity.

Smart Links and Notes 5/24/2010

Apologies to all for not posting much recently — the usual confluence of other commitments intervened, as did several commitments to write for Maple Street Press publications. Those are (mostly) done, and I have a variety of ideas for the site, and I hope to write those up and get them on the site. But for now, linkage:

Two very important posts on fourth downs. First, the Mathlete’s breakdown (available at mgoblog) of fourth down decision making is worth it for the graphs alone (see below). Also Brian at Advanced NFL Stats reposts his powerpoints about when to go for it on fourth down.

Fourth down decisionmaking chart

NFL players channel MC Hammer. I may have previously linked to this, but I recently stumbled on it again. It remains shocking:

The 78 percent number (i.e., 78% of NFL players go bankrupt within two years of retirement) is buoyed by the fact that the average NFL career lasts just three years. So, figure a player gets drafted in 2009, signs for the minimum and lasts three years in the league: He will have earned about $1.2 million in salary. Factor in taxes, cost of living and the misguided belief that there will be more years and bigger paydays down the road, and it becomes a lot easier to see how so many players struggle with money after their careers end.

Runningback by committee? TheDoc notes the apparent end of Southern Cal’s “runningback by committee” system. He quotes Lane Kiffin saying:

“We would rather not be in a big committee thing,” Kiffin said. “As a running back, you get better throughout the game because you get used to what’s going on, how is the defense playing, are we able to get the backside cuts, how are the D-tackles playing the different blocks.

“You have to get a rhythm, and so I would rather find one or two guys. So that’s our job, to figure out this fall who are those guys going to be.”

I don’t really agree; I’ve always been fine with the runningback by committee (though, admittedly, I was never a runningback forced to play in such a committee). I think different backs have different talents; wear and tear on backs adds up; I don’t believe there’s much evidence proving that runningbacks actually “improve as the game goes on” (though I’d love to see contrary evidence); and you don’t hear much complaining about a “committee approach” to rotations at other positions, especially defensive line. Moreover, I think freshness is underrated, but, in the end, at long as the backs are close in talent I don’t think it makes much of a difference (except to the players, as in a single-starter system one will reap all the benefits while the others will be relegated to back-up status). Finally, as evidenced by this post from the Mathlete, not having a returning starter at runningback doesn’t seem to hurt your chances of success at all, thus one can fairly say that, holding talent equal, the difference between using one back or another is small (though that comparison is a bit of apples to oranges).

The Wolfpistols. Holly previews the Nevada Wolfpack over at Dr Saturday.

High school athletes and concussions. From the NY Times.

- Do you know who the all-time leaders in receiving yards per game are? From the Pro-Football reference blog.

Charles Goodell: Senator, opponent of Vietnam, father to NFL Commissioner Roger Goodell.

The worst run defenses in NFL history, by the numbers.

Why do colleges have football teams? This debate rages, but I’m still waiting for hard evidence of the good (or bad) reasons for it. One view: “The evidence is mixed, but some papers find a connection between athletic achievement and student quality, or athletic achievement and alumni donations. I suspect the donor connection is the key, but we also must ask what exactly colleges and universities seek to maximize.” I suppose, having already graduated, I shouldn’t really care anymore because, even if it is bad business or scholastics (not saying that is so), I enjoy football (obviously) and get to be a free rider on whomever is paying for the team, like fans, students (many universities now require students to automatically buy in to a ticket program), donors, etc.

On those awful advertisements for colleges played unnecessarily though out football broadcasts: “If you like our football team, you’ll love our chem labs full of Asian students.”

- Is watching football worthwhile? You know, metaphysically speaking: “Dissatisfied with the academy’s somewhat elitist dismissal of sport as just another capitalist banality, Gumbrecht wants to argue that there is more to the roar of the crowd than mere tribalism. To Gumbrecht, the current mass appeal of sports represents more than the manipulation of the masses by advertising corporates. There is something almost transcendental about sport; some aesthetic quality that unites us with the Greeks, the Romans, even with the gods themselves as we admire the movement of a body, or revel in the million to one victory.” Plus, you know, you get to watch people get hit.

How QB-like does Michigan’s Denard Robinson look to you? I, like many, think that for Michigan’s offense to score like Rodriguez wants it to against in-conference foes it will have to be Denard Robinson that becomes a real quarterback. So, behold, every snap of his from Michigan’s spring game. Is he there yet? I’m not sure, though I did like the pass off the bootleg action from the under-center I at around the .40 second mark — turned his shoulders nicely on that one. (H/t mgoblog.)

Football and religion: Is the hand of God evident in a well designed screen pass?

Sentences to ponder

From the Pro-Football Reference Blog:

[Imagine w]e have two teams that both average a whopping 14 yards per attempt. One team completes 100% of its passes; the other 50% (for 28 yards per completion). If I were to model those two, it seems pretty clear that the team that completes 100% would score more. They would score on virtually every possession, only failing to score in limited cases where their 3 consecutive completions net 9 or fewer yards. The 50% team would also score a lot, but string together a few more droughts. I suspect my 100% completion team with 14 yards per attempt would average about 60 points a game, while the 50% completion team would average closer to 50.

At the other end of the spectrum, we have two teams that average 3 yards per [pass] attempt. If one of those teams completed 100% of their passes, they would struggle to maintain drives or even get them started [or would routinely end on 4th and 1…], while a 25% completion team would occasionally string together first downs and get into scoring range. Neither would score much at all, but if I were forced to watch both teams for 24 hours straight as punishment for all my transgressions, I’d take the team with the yards per completion to win in a non-shootout.

slots

And later in the piece:

[I]t is pretty clear that the QB’s in a Don Coryell-based offense (Fouts, all of the Redskins QBs of the 1980’s and early 1990’s, and the Rams and Chiefs recently) are undersold by passer rating relative to adjusted net yards per attempt in terms of the value they provided, and the West Coast passers are oversold, and its because of the different philosophies as they affect completion percentage.

Smart Football Podcast 8/31/09

I did a post-cast with the brilliant Bill Connelly of Rock M Nation (and Football Outsiders). Wherein we discuss (me incoherently, Bill with great precision) the following:

1. Missouri vs Illinois
2. The future of Missouri’s spread offense moving from Chase Daniel to Blaine Gabbert
3. The role (and limits) of college football analysis and statistics
4. Rich Rodriguez and NCAA practice rules
5. A PTI-style, Big 12-themed rapid fire round

Thanks again to Bill for running the show. The technical kinks are still to be worked out (including my sounding like I’m telecommuting from the Ozarks), but enjoy the foolishness.

Smart Football/RockMNation podcast 8/31/09

(Note that I was having issues with the embedded audio. If it’s not working I’ll work on it, but the download link should work.)