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Tuesday, September 27, 2011

Stat of the Week - # of Plays

So far this season, Auburn's opponents have run 101 more plays than the Tigers, putting them well behind the second worst FBS team in play differential (Tulsa at -73). But in those 100 fewer plays, Auburn has score 13 more points than their opponents (and in just the right proportion to put Auburn at 3-1). In fact, the correlation this season between play differential and point differential is only .279, with Oregon and LSU also among the teams that have defended more plays than they have run themselves.

What do all of these teams have in common? What do all good teams have in common? Higher yards per play than their opponents. Oregon, for example, has been averaging more than 2 yards per play more than their opponents this season. Across teams, the correlation between points per possession and plays per possession is only r=.274 while the correlation between points per possession and yards  per play is a massive .878. In other words, few teams make a living on long, sustained drives. Instead, they score points on big plays and short fields.

And more plays do little to help a team rack up more yards per play by wearing out defenses. The correlation between yard per play and number of plays is weak, and can be totally explained by plays per possession - teams get more plays because they get more first downs. In other words, more plays on their own do nothing to increase a team's offensive efficiency.

Monday, September 26, 2011

BPR Poll Week 4

BPR is the ultimate in computer ranking. (Click here for an explanation.)

Wednesday, September 21, 2011

Don't be Naive: Conference Realignment is NOT about Greed

In real life, I'm a social scientist. I, like other social scientists, study human behavior and the factors that influence decision making. And I'm better at it than most. And if you think college football realignment is motivated by greed, you're just being silly and naive.

In short, too many people are making the leap that because a decision will generate more revenue for an institution, this decision is motivated by greed, the "excessive or rapacious desire, especially for wealth or possessions". (People make the same mistake when discussing the actions of "the government" or of "the state", as though it is a single-minded entity.) But institutions do not make decisions, people within institutions make decisions, so to understand the incentives at work, we must understand how these decision-making individuals benefit from conference realignment. How do the boards of regents, university presidents and, to a lesser degree, athletic directors benefit?

Before we visit this question, though, let me pose another question - if a football program generates more revenue, where does that revenue go? Who benefits? Some goes to pay for better coaches and some to pay for better facilities. Some money goes to pay for field hockey and water polo (coaches, facility maintenance, equipment, travel), especially as budget crises pull funds from these smaller sports. So the real beneficiaries are coaches, school bus drivers, the people that build indoor practice facilities, and the college athletes themselves. While these people may be whispering in the collective ears of the decision makers, they are kept well away from the controls, and coaches, outside of Norman, Oklahoma, generally try to distance themselves from realignment talk.

And then there are the college football fans. Many fans of particular programs are screaming for realignment, and some boosters, like the coaches and indoor practice facility builders, may occasionally have the ear of a university president, but they, again, are not the one's making the decisions. And even if they did have more influence, fans and boosters are not looking to make a buck from realignment. They want the resources and exposure to attract and train better athletes and better football teams.

And now we return to the real decision makers. What motivates R. Bowen Loftin and Kenneth Star? People in these positions are not looking to make an extra buck wherever they can - their reputation among a class of intellectuals is worth far more. And Loftin will not make more money and Star less money when A&M leaves for the SEC, at least not directly or immediately - or ever. But they are judged for their management of university resources, including the athletic departments. Finding funding for bull riding in a budget crisis is a feather in their cap. Finding the resources to hire the best coaches and build the best facilities to build a better college football program is a much bigger feather, or perhaps even the cap itself (so much so, that the other feathers are sometimes lost). The people that Loftin has to please are not interested in how much money the football program is generating for its own sake, but, like the fans, they appreciate a football program that brings positive attention to the university.

So while there are many people that want realignment, and want the extra revenue from realignment, they-fans, coaches, athletic directors, university presidents, boosters, everyone but the builders of indoor practice facilites-are ultimately motivated by building a better football program and, to a much lesser extent, a better volleyball program. They aren't greedy - money is only a means - but the best things in life aren't free. And I will never criticize anyone - athlete, coach, fan, booster, university administrator - for wanting their football to be a better football team.

Tuesday, September 20, 2011

BPR Poll

BPR is the ultimate in computer ranking. (Click here for an explanation.)

Wednesday, September 14, 2011

Magic Numbers, Magic Percentages, and Magic Probabilities

The logic here could be applied to any sport, but it is most applicable in Major League Baseball (and it is in this context that I had the idea). I love magic numbers in baseball*. As a Rangers fan, I usually start tracking their magic number before the All-Star break. There is something so definitive about a magic number. But magic numbers really tell you very little about how likely it is that a team will win a division.

So, to extend the magic number, I've added magic percentages and magic probabilities. The magic percentage is the magic number divided by the number of games remaining for both teams. For example, if a team has 10 games left to play and a they have a 3 game lead on a team that also has 10 games left, the leading team will need 40% ((10-3+1=8)/(10+10=20)=.4) of those 20 games to have a favorable outcome - they win or the second place team loses - to clinch. The second place team in this situation has a magic number of 14 and a magic percentage of 70% - they need 70% of games to have a favorable outcome to clinch. The two magic percentages do not add to 100% because there is the additional possibility that the teams tie at the end of the season, which would not satisfy the requirements of the magic percentage for either team.

Calculating the magic probability is a bit more complicated, but there are plenty of tools to help. Here's the logic: if we know a team needs 40% favorable outcomes, what is the probability that they will get that and clinch the division? We can calculate this, using some simplifying assumptions, by drawing on the binomial cumulative distribution function.We are going to assume that the team has a 50% chance of getting a favorable outcome in each game (it will actually be a bit higher for their games, but a bit lower for their opponent's games, so it averages out, more or less). With that assumption, we can go to the calculator below. n is the number of games remaining for both teams (20 from the example above), p is .5, Prob. X is should be set to "more than", and the next blank takes the magic number minus 1. Hit compute. So, for the example, we find that a team with a three game lead with 10 games left to play has a 87% chance of winning the division (without taking into account schedule or other idiosyncrasies). If both teams win the next 5 games, the magic number will have shrunk to 3, the total remaining games to 10, and the magic probability will have risen to 95%.

*I'm going to assume above that readers are familiar with the concept of magic numbers, but for those that aren't, a team's magic number is the number of favorable outcomes-wins for Team A or losses by the team in their division with the best record (not counting the Team A, of course)-they need to clinch the best record in the division. It's calculated as Games Remaining-Lead in the Loss Column+1. If the team is not in first place, Lead in the Loss Column will be a negative number. So, if a team has 10 games left and a 2 game lead on the second place team, their magic number is 9. They can clinch the division by winning 9 games, by the 2nd place team losing 9 game, or some combination thereof.