Game Probabilities - Week 6

Weekly game probabilities are available now at the nytimes.com Fifth Down.This week I also lead-in with my take on some differences between explanatory and predictive models.

Team Efficiency Rankings - Week 6

The team rankings below are in terms of generic win probability. The GWP is the probability a team would beat the league average team at a neutral site. Each team's opponent's average GWP is also listed, which can be considered to-date strength of schedule, and all ratings include adjustments for opponent strength.

Offensive rank (ORANK) is offensive generic win probability, which is based on each team's offensive efficiency stats only. In other words, it's the team's GWP assuming it had a league-average defense. DRANK is is a team's generic win probability rank assuming it had a league-average offense.

GWP is based on a logistic regression model applied to current team stats. The model includes offensive and defensive passing and running efficiency, offensive turnover rates, and team penalty rates. If you're scratching your head wondering why a team is ranked where it is, just scroll down to the second table to see the stats of all 32 teams.

Click on the table headers to sort:

Irrational Play Calling

As if you need any more evidence of how irrational many coaches can be when facing a 4th down, here’s some more.

In ‘no man’s land,’ the region of the field from the opponent’s 30-35 yd line, punts don’t buy you much and field goals are just above 50/50 propositions. Going for the conversion occurs fairly frequently, particularly on 4th and short. This is the confluence of 4th down decision making where all 3 options are reasonable choices.

But once a coach has decided that going for it is not worth the risk, he can then choose between attempting a FG and punting. Neither of these options is affected in any way by distance to go. Only field position matters. A field goal is just as rewarding and just as risky on 4th and 1 from the 30 as it would be on 4th and 15 from the 30. Same goes for punts. Distance to go should only affect conversion attempts. It would be irrational to base a decision between a FG and punt based on something that only matters when attempting a conversion. But that doesn’t stop NFL coaches from doing exactly that, a fact first noticed by commenter 'Jim A' last season.

Game Probabilities - Week 5

Weekly game probabilities are available now at the nytimes.com Fifth Down.This week I also lead in with my take on how much luck can have to do with game outcomes.

Efficiency Rankings - Week 5

The team rankings below are in terms of generic win probability. The GWP is the probability a team would beat the league average team at a neutral site. Each team's opponent's average GWP is also listed, which can be considered to-date strength of schedule, and all ratings include adjustments for opponent strength.

Offensive rank (ORANK) is offensive generic win probability, which is based on each team's offensive efficiency stats only. In other words, it's the team's GWP assuming it had a league-average defense. DRANK is is a team's generic win probability rank assuming it had a league-average offense.

GWP is based on a logistic regression model applied to current team stats. The model includes offensive and defensive passing and running efficiency, offensive turnover rates, and team penalty rates. If you're scratching your head wondering why a team is ranked where it is, just scroll down to the second table to see the stats of all 32 teams.

Click on the table headers to sort:

Marvin Lewis Gets Bold In Overtime

The Wall Street Journal's 'Numbers Guy' Carl Bialik asked me the other night about the Bengals' 4th and 11 conversion attempt late in overtime against the Browns. With a just over a minute left in OT, the Bengals faced a 4th and 11 from the Cleveland 41. Quarterback Carson Palmer was able to scramble for 15 yards and a first down, and Cincinnati went on to kick a field goal to pull out the win. At the risk of sounding like a broken record on the topic of 4th down decisions, here's a summary of what I told Carl.

Raheem Morris Is A Really Optimistic Guy

Trailing by 6 points with 4:30 left in the game, the Buccaneers faced a 4th and goal from Washington’s 4-yard line. The Bucs kicked the FG to make the score 16-13 and went on to lose. Columnist Gary Shelton of the St. Petersburg Times wants to know why head coach Raheem Morris didn’t go for the touchdown. That makes at least two of us.

I’ll spare everyone the math, but all things being equal the better decision would have been to go for it. Kicking the field goal gave the Bucs a 0.19 Win Probability (WP). Attempting the TD would net a 0.29 WP on balance. Morris’ decision basically cut his chances of winning by a third.  Sure, the particular "flow" and match-ups of the game are factors, but those considerations are usually overblown. Besides, if the game is close enough for it to matter, then the two teams are probably fairly equal, at least for that day.

But that’s not the point of this post. The more interesting thing is the glimpse inside the mind of an NFL coach. Here’s what Morris said when asked about the decision:

'Touching' the Passer and Belichick on 4th Down

Should it be called “roughing” the passer or “touching” the passer?

The talk of the NFL today is about the two roughing the passer calls in the Baltimore-New England squeaker yesterday. Judging from comments around the blogosphere (plus Rodney Harrison and Tony Dungy), the verdict on whether those calls were justified is pretty clear. In this post, I’ll mathematically prove that those calls were errors…No, just kidding. But what I will do is look at how crucial those calls were to the Patriots’ win. I'll also take a look at a critical 4th down call.

Both drives in question ended in touchdowns for the Patriots, worth a total of 14 points in their 26-20 victory over the Ravens. It might be temping to just subtract 14 from 26 and claim the Ravens would have won, but it’s obviously not that simple. From the point we change anything within the game, everything after that would unfold differently. We need to look at it probabilistically.

Full Review of Game Theory Run-Pass Balance Study

A new paper on game theory and run-pass balance in the NFL, Professionals Do Not Play Minimax: Evidence from Major League Baseball and the National Football League, says that offenses run too often and play calling is too predictable. The authors, Kenneth Kovash and Steven Levitt, construct a success metric to value the outcome of NFL runs and passes from the 2002-2005 seasons. Then using regression models, they estimate and compare the values of a typical run and a typical pass. They also construct a regression to test if play calls can be predicted to any degree based on the previous play call.

Game Theory

Game theory tells us that in a 2-player zero-sum game, if both players are playing the optimum mix of strategies, the long-term average payoff from each strategy will be the same. If you have two general strategy options, like run or pass, you can’t just choose one of them all the time. That would make the defense’s job pretty easy. So you need some sort of unpredictable mix of strategies. The question is, what’s the optimum ratio?

Roundup 10/3

Neil Paine, the new administrator at Pro-Football-Reference.com ranks all QBs in NFL history by their six best seasons. Ken Anderson, John Unitas, Roger Staubauch, Steve Young, and Peyton Manning come out on top.

Neil also points out that Peyton Manning is dominating the Adjusted Yards per Attempt stat so far this year and since 1998. Kurt Warner, Tom Brady, Drew Brees, and Rich Gannon trail. Some surprises (to me) on the list of top 20 QBs include Chad Pennington, Jeff Garcia, and Doug Flutie.

For those interested in the historical comparisons between the AFL and NFL, Jason Lisk puts a bow on his series on draft classes.

Game Probabilities - Week 4

This year the weekly game probabilities are featured on the nytimes.com Fifth Down. Each week, I'll post a link to the probabilities at Fifth Down.

The model has been updated this year to add the 2007 and 2008 seasons. Previously, it was based on data from the 2002-2006 seasons.

The only significant change is that I have re-included defensive interceptions this year. I had based the decision to exclude them on the lack of auto-correlation for team defensive interception rate from the first half of the season to the second half in both 2006 and 2007. However, the 2008 season indicated a relatively strong auto-correlation. In short, I based my previous conclusion on too small a sample. Ultimately, I adjusted the model weight of defensive interceptions by how well it predicts itself throughout the season on average in those three seasons.