January 21, 2019

Geek Speak: Why Every Yard Matters, The Relationship Between Yards & Points

One of the most important statistics in football is also one of the most basic – total yards. If you knew nothing else about two teams,  be it records, point spread, who was favored and who was the underdog or any other in game stat, but you knew who had the most total yards you would have a 75% chance of picking the winner.

Closer to home Clemson went 9-1 in games where they out gained opponents and 1-2 when being out gained.

It’s usually at this point that football savants remind me of the teams who gained more yards than their opponents and lost as proof that I’m “wrong”.  Maybe they feel like I’m taking the physicality and strategy out of football by assigning a value to each yard gained (more on this below), but really the point of this is to reinforce the importance of each and every yard gained or lost, emphasizing the importance of the physical nature and accompanying strategic moves that are part of the game.

Many prefer black and white, yes or no and disdain odds and/or probabilities.  The only metric they are interested in is points.  Getting more than the other team guarantees a win 100% of the time. Nothing else matters.

Yet if a team starts at its own 10, drives 40 yards, punts and their opponent is backed up inside the 10 the team gets 0 points for that drive – but those 40 yards have a value.  Field position has been changed, and so have the odds of winning because of those 40 yards that yielded 0 points.

Every yard is important, at least while the game is in doubt.

Clemson scored on offense, defense, and special teams in 2014.  However, the vast majority of touchdowns (and therefore points) came on offense (89.6% of Clemson touchdowns came on offense) and involved gaining some amount of yards.  Sometimes it takes a lot of yards, sometimes just a few, but by and large you score by gaining yards.

The graph below plots points and yards of every game over the last four years (between 2 FBS teams). The slope should tell you all you need to know.

Yards & PointsYes, there are outliers, but the picture tells a story in 3 words – yards equal points.

Better than that generic “yards equal points” phrase, we are able to determine exactly how many points a team can expect to score based on yards gained.  Even more intriguing than that is the close to perfect symmetry of the numbers below.  For almost every 11 yard increment one additional point can be expected.

Expected Points Per Total Offense

There are no exceptions, meaning there is no instance where gaining more yards means you should expect less points.  It sounds amazingly obvious, but you’d be surprised at how many football fans believe total yards is an irrelevant metric.

Of course, the yards you gain are only part of the game and are therefore relative.  You can expect to score 36 points if you gain 490 yards, but if your defense gives up 510 yards you will most likely lose.

That doesn’t mitigate the overall point, which remains valid – yards are important because the more yards you gain the more points you are likely score – without exception, statistically speaking – and that means the more likely you are to win.

Total yards is certainly not the only metric I use when determining win probabilities, but its an important one that I give significant weight in my calculation.

 

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: