Does "the law of diminishing returns" apply to passing?

by Jim Glass
Does "the law of diminishing returns" apply to passing? If so, does it mean anything for team strategy?

Does diminishing returns apply to passing? As a QB passes more, should the effectiveness of his passing be expected to decline? Or do mismatches rule and quality win out in NFL contests, so a top-quality QB's performance should be expected to be consistent during an entire game – or even rise as he finds the weaknesses in a defense and maybe even "breaks" it?

Diminishing returns isn't really a law so much as the observation that people logically put a resource to its most productive use first, then to its second most productive, and so on, so the return from its use incrementally declines. This phenomenon is all around us in modern life.

In football the logic is that teams use the pass plays they can execute best for greatest results first. But when teams throw a lot they must move beyond those few plays -- so their AYA will fall to significantly below its level in few-attempt games.  There's lots of anecdotal evidence supporting this idea.

Passing in the Post Season

by Denis O'Regan.

Using post season data and a logistic regression approach I've taken another look at how completion rates are dependent on how far a quarterback is throwing the ball in the air.

I've made the dependent variable the outcome of the pass attempt (1= a completion and 0= an incompletion) and used the position on the field where the ball is caught or not caught by the receiver as the independent variable. Yards after the catch is discounted if the pass is caught.

I've run regressions for Rivers, Roethlisberger, Brady, Rodgers and Manning, seperately pooling all their attempts in the post season since 2006. I've also included Rex Grossman as an example of a not particularly accurate QB and Mark Sanchez, whose completion rate appears to thrive in the post season and is on an upward career curve.

Eight Football Stats I Hate and why the professional pundits put so much effort into selling them to us.

by Jim Glass

I may be getting old and cranky, but TV analysts repeatedly, breathlessly throwing out junk stats to me during all the big games is getting to me. And I expect it will only get worse, because there is something about the culture of football that encourages them to do it, makes it profitable for them -- and football is a business.

Here are some of the stats I really dislike and why, followed by a little editorializing on why NFL game producers and their attending media put so much effort into pushing them.

Luck point through the Divisional Playoffs

by Bruce D

No luck, no win this past weekend for the top 2 lucky teams.

Total team luck points through the play-offs(week 19):

Luck is tracked to better analyze a team's true ability and to help predict results of upcoming games where some may not know what portion of a team's record and points performance was due to just luck.

For a more in-depth explanation of what "luck" points are, go to a previous post here.

Belichick’s Overlooked Blunder

by Bryan Davies

Amidst the expletives and tongue-in-cheek comments thrown around by Jets and Patriots this past week (ok, mostly Jets) was an actual game to be played on Sunday. And, like any football game, there are a number of decisions that coaches are given the opportunity to screw up. With the underdog Jets ahead for nearly the entire game, it seemed that a lot of the tougher decisions needed to be made by Belichick and the Patriots. A fake punt on 4th and 4 from their own 38 with time winding down in the first half, a two-point conversion in the third quarter, a 4th and 13 rather than a 52-yard field goal. Well, we know which ones turned out to be good decisions, but were they objectively good decisions without the benefit of hindsight?
Well the truth is, I’m not going to address any of those situations. I’m sure you’ll find enough analysis, both good and bad, that will address them extensively. In the spirit of being an overly pedantic statistically-minded football fan, I thought I’d address Belichick’s incorrect decision to go for an extra point rather than a two-point conversion following the Brady-Branch touchdown with less than 30 seconds to go in the game. In fact, when down 14 points, it’s almost always a better decision to go for two following a touchdownlate in the game.

An Example of TWP Calculation

by Andrew Foland

I scanned in about 20 points of WP by hand from the New Orleans-Seattle game WP chart, and used the previously described method for generating the “TWP” that combines the WP model with the input MWP (which favored NO by 59%, in this case.) The plot of the TWP is shown below together with the WP chart.

As you can see, late in the game the MWP consideration doesn’t change the WP very much. This is actually as expected. The better team is expected to have already done better by late in the game. If it is not already ahead, the high randomness of the few remaining possessions overwhelm the average expected advantage of the better team. This is a restatement of the “variance is the friend of the underdog” motto.

Win Probability and Point Differential

by Andrew Foland

This article is an exercise in extreme pedantry: I’m going to ask a question whose answer is obvious, conduct some research, and conclude that the answer is, in fact, the obvious one.

As noted in my earlier writeup, an average team with a 13 point lead after five minutes would have a win percentage of 80%. (This, of course, is nothing more than inputting some numbers into the front end of Brian’s WP calculator—all the real work is Brian’s in creating that WP and the calculator front end.) Being only 5 minutes in, one can approximately take this result as a proxy for the result of, “If an average team had started the game with a 13 point lead, it would win 80% of the time.” (We’ll do something a mite more sophisticated in a moment, but this is the basic idea.)

Of course, no team begins the game with a 13 point lead. However, some teams do have a 80% generic win percentage. Is there a useful relationship between these two points?