## Underdogs, Reducing Possessions, and Super Bowl XLII

In the last article, I made the point that underdogs have a better chance of winning a game when each opponent has fewer possessions. Specifically I wrote, "The more possessions each team has, the more likely it is the better team is going to eventually come out on top. With fewer total possessions, the underdog has a better chance to win because randomness plays a bigger role relative to team ability in a game’s outcome." This article will estimate just how much an underdog can benefit by reducing the total number of possessions in a game.

I built a crude simulation of a football game in the PHP programming language. By specifying the number of possessions for both teams and the scoring rate of each team, a simulated score and winner can be determined. By running the simulation many times, we can get a good estimate of the win probability for various numbers of total possessions.

But first, we need to pick a couple of teams as guinea pigs. One needs to be a big underdog against the other. Hmmm, let's see. How about the Giants and Patriots?

The Patriots scored touchdowns in 42% of their possessions in 2007. And 13% of their possessions resulted in field goals. They gave up TDs in 17% of their opponents' possessions and allowed FGs in 7% . In contrast, the Giants scored TDs in 21% of their possessions and kicked a FG in 12%. They allowed TDs in 19% of their opponent possessions and gave up FGs in 11%. The table below summarizes each team's respective drive stats.

 Scoring Rate NE (%) NYG (%) Own TDs 42 21 Own FGs 13 12 Opp TDs 17 19 Opp FGs 7 11

If we assume that the each team will score according to the mid-point between each offense's and defense's scoring rate, we can construct a fairly solid model. For example, given the Patriots' 42% offensive TD rate, and the Giants' 19% opponent TD rate, we could estimate the Patriots would score (42 + 19) / 2 = 30.5% of the time. (I realize this is pretty rough, but it suits the simulation's purpose.)

Unfortunately for New York Giants fans, the Patriots won the first simulation 38-7. That was for 12 possessions for each team, the most common number of team possessions in the NFL. But one simple simulation is pretty pointless. After 10,000 of them however, New England won 75.6% of the games and the Giants won 20.5%, with 3.8% of the games going into overtime.

But what if each team only had 10 possessions? How do the underdogs fare? The Patriots' win 72.7% of the games and the Giants win 22.4%. Reducing the number of possessions does boost the chances of the underdog, but only slightly.

The table below lists typical numbers of possessions for each team in NFL games along with the simulated probabilities of winning for each team.

 Possessions NE Wins NYG Wins Overtime 9 71.4 23.5 5.1 10 72.7 22.4 4.9 11 74.0 21.5 4.5 12 75.5 20.7 3.8 13 76.5 20.0 3.5

First thing to note is that the Giants have an improbable challenge, no matter how few possessions to which they can limit their opponents. This method appears to confirm my standard logistic regression efficiency model that gives the Giants about a 1 in 4 shot at the title. But that's nothing to sneeze at. How much sleep would you get if you knew you had a 25% chance of your life savings being wiped out by morning? It's not a guaranteed victory for New England by any stretch.

The fewer the number of possessions, the greater the chance of upset. Letting the clock run is in the Giants' interest. Did you hear that Plaxico? Take the hit and stay in bounds, (as long as the score is close). You'll be helping your team more than you could ever understand.

### 2 Responses to “Underdogs, Reducing Possessions, and Super Bowl XLII”

1. Anonymous says:

I think the timing rules are such that the clock does not stop running when players go out of bounds unless it is within the last 5 minutes of each half. I may be wrong on the time when that starts, but I am pretty sure it doesn't stop if a player goes out of bounds in the first quarter.

The point about reducing possessions is a good one. My strategy, though, would be to try at least one (if not more) surprise onside kicks in the course of the game (on the thought that field position matters less against NE because they score on so high a number of possessions, even those deep in their own territory), be very aggressive on fourth down and not settle for field goals unless absolutely necessary. And I probably wouldn't punt if I had 4th and 10 at the NE with 9 minutes left trailing by 9.

2. Brian Burke says:

Good catch. I'm embarrassed to say I hadn't realized that. I looked up the rules and here's how it works:

1. The game clock does stop every time the ball goes out of bounds.

2. The game clock will restart when the ball is re-spotted except:
a. In the final 2 min of the 1st half, or
b. In the final 5 min of the 2nd half.

3. Inside 2/5 minutes remaining, the game clock will restart on the next snap.

So staying in bounds would usually only buy you 10-15 seconds, not the 30 or 40 seconds I had thought. It would still help, just not that much.

Totally agree on the 4th down point. I'm a big believer in going for it on 4th down far more often than it is currently practiced, especially when trailing. For the past few weeks I've been working on a project to help prove that point.