March 18, 2019

Yards Still Matter

If you spend any time on this site you know that one of my favorite college football metrics is also one of the most straightforward – total yards.  With the exception of yards per play, and it’s close, you’d be hard pressed to find a metric that correlates more to winning than total yardage differential between two teams.  Why?  Because yards = points.

Every time I hear someone say yards don’t matter – and provide an example of a game where a team with less yards won – my head wants to explode.  Yes, there are exceptions to the rule.  Just like there are exceptions to “You have to win the turnover battle” or “You have to run the ball to win”.  For every example you provide of a team winning despite having less total yards, I can provide more where a team won the turnover battle and lost.

If you made it through freshman stats then the graph below should tell you a story.  I’ve plotted every college football game from 2011 through 2015 (D1 vs. D1 only, 3,580 games and 7,160 data points) with yards and points.  Notice the slope of the line that goes through the data points.  It’s pointing up, as in more yards means more points.

Points and Yards Graph 2011-2015

This is significant for Clemson because one of the narratives of the offseason is that the Tigers defense lost a lot of talent and will have to “rebuild”. Fair enough.

In the period covered, teams that reached the magic 500 yard mark won 79% of the time, without regard to any other metric.  Clemson has reeled off 10 straight (and counting) 500 yard games.  Just by the fact that your offense is gaining 500 yards means you are highly likely to win.  

But it gets better.

The Clemson defense gave up 313.0 yards per game in 2015.  For arguments sake, lets say the Tigers 2016 defense regresses to “average”, which in NCAA terms in 2015 was 400 yards per game.  That’s an additional 87 yards per game given up (27.7% increase).

In our mythical game Clemson gets 500 (or more) yards and gives up 400 yards (regressed to average).  What are the chances the Tigers win?  Over the same time period (2011-2015) teams with this profile won 94% of the time (671-43).

Yards+Points Diff

To recap, the Clemson offense is likely going to be so good that the Tigers can absorb a defensive regression to “average” and still have a high probability of winning.

Obviously, there are no guarantees and every game is an independent data point on a graph such as the one above. The Tigers may reach 400 yards in one game (reducing the odds of winning) and 600 (very high probability of winning) in the next.

The point is an offense that’s likely to reach 500 yards in any given game and give up an “average” amount in the same game is still likely to win and is also why our early win probabilities have the Tigers favored in all 12 games.

As we saw in the championship game 500 yards of offense a game is not a 100% guarantee of a win, but 500 yards of offense combined with holding your opponent to 400 or less is about as close as it gets.

Offensive Drive Metrics

With Cole Stoudt at the helm for the next several weeks we can anticipate a faster pace for the Clemson offense, but it’ll be interesting to see if there is any significant change in the numbers below.  Obviously, a fair amount of these numbers include Stoudt’s efforts to date considering he played all but three series at Georgia and all but a quarter against Louisville.

I haven’t run the numbers to compare what happened under Tajh Boyd, but it seemed like there were drives that took more time off the clock.  Only 3 drives have lasted over 5 minutes and the Tigers have been boom (as in touchdown) or bust (as in 3 and out) for the most part.  Obviously, the running game effects these numbers and I’m not sure we’ll see significant improvement there this week.
Clemson Drive Chart 2014 6Clemson Drive TOP Chart 2014 6

Geek Speak: Total Yards Matter – 2014 Version

While I don’t believe total yardage is the “end-all, be-all of football” it’s pretty clear to me that total yards are an important stat in college football.

Besides the obvious – it generally takes yards to score points – I have some numbers that back up this theory.

There are many guys smarter than me that say total yards mean little, are an “overrated” or “simplistic” metric and spend many hours devising complicated formulas to prove why that is.

I’m not smart enough to understand all of the mathematics behind those theories, but my general operating theory is “the simpler the better”.

It’s difficult to find a simpler metric than total yards, and this seems to give those smarter than me fits.

Specifically, out gaining your opponent is important.  The more the better.  If you think about it, out gaining your opponent takes into account many factors that occur during the game.  If you turn the ball over consistently you are likely to gain less yards, score less points and win less often, for example and using the difference between teams total yardage also means defense is factored into the equation.

So while gaining  yards is important, this analysis looks at the difference in yardage between winners and losers.  Another way to put it is, if Team A gains 600 yards and gives up 575 yards in game 1 and gains 125 yards and gives up 100 in game 2, Team A has the same odds of winning both games.

It’s not about the number of yards you gain, it’s about the difference between the number of yards you gain and the number of yards your opponent gains.

The charts and graphs below cover 2,116 games (6 games resulted in teams having exactly the same number of yards) between Division I teams from 2011 through 2013 and tell a simple story: Outgain your opponent and you will likely win. The more you outgain your opponent the higher your odds of winning.

Winning Pct by TYA Chart

Winning Pct by TYA Graph

A little further proof that yards matter? Teams with more yards than their opponents cover 64.6% of the time. And, as with the winning %, the higher the yardage differential the more likely a team is to cover, without exception.

 

Cover Pct by TYA Chart

Cover Pct by TYA Graph

Using the Pearson Coefficient I found a solid 0.606149 correlation between total yard differential and winning.

How did Clemson fare using this metric in 2013? I’ve previously posted on why I wasn’t that worried as Clemson fell behind in the Orange Bowl vs. Ohio State and the Tigers were 9-1 (lost South Carolina) when they outgained their opponent and 1-1 when being outgained (won Georgia, lost Florida State). Against the spread the Tigers were 6-5 when outgaining an opponent and 1-1 when being outgained.

No, total yards aren’t the end-all, be-all of football. But total yards, specifically when compared to your opponents total yards, matter and this simple metric can also increase the odds of picking the team that’ll not only win, but cover the spread, too.

It’s important not to confuse correlation with causation and I’m not saying having more total yards causes teams to win by itself.  Other factors (turnovers, for example) can cause a team to have more (turnovers gained) or less (turnovers lost) total yards and win or lose the game.

I’m saying total yards is an important factor in determining winners and losers, more than many want to acknowledge.

 

Analyzing Georgia’s 2012 Statistics

If you’re like me you take NCAA statistics and rankings with a grain of salt. Almost everyone understands that gaudy statistics, to varying degrees for different teams, are enhanced by the cupcakes on the schedule.

Just how much? That’s what I endeavored to find out as I looked into both Georgia and Clemson’s offensive numbers for 2012.

The tables below show the differences between what both Georgia and Clemson averaged against BCS teams, Non-BCS teams and FCS teams.

Georgia played 2 Non-BCS teams, 1 FCS team and 11 BCS teams in 2012.

Clemson played 1 Non-BCS team, 1 FCS team and 11 BCS teams in 2012.

Georgia’s offense, while still prolific, was noticeably lower in rushing yards and points when playing against BCS defenses. Some dropoff is expected, but 16 points and 106 yards rushing seems like a high number.

Clemson’s point output dropped by 12, but interestingly enough the Tigers ran the ball better and still averaged over 500 yards a game against BCS competition.

This is typically where someone chimes in with the “strength of schedule” argument and it’s true that on average Georgia faced tougher defenses. But not that much tougher. The defenses Georgia faced averaged a 41.5 ranking, while Clemson’s defensive opponents averaged 49.4.

The teams had three common opponents – Auburn, Georgia Tech and South Carolina and both faced 2 top 10 defenses, while Clemson faced 5 top 20 defenses compared to 4 for Georgia.

Georgia’s offense is potent, but it’s interesting to note the Dogs precipitous drop in rushing against BCS teams, even if most of those defenses had SEC speed.

Total Yards Matter: Clemson Version

On Tuesday I explained why total yards matter in the big picture of college football – total yards correlates to points at a much higher rate than other statistic in college football.

I realize however, that many of those that read this site don’t care about this stat for college football as whole, but rather what it means for Clemson in particular.  The answer: The same thing.

While the number of plays run for Clemson has a strong (but smaller) correlation to points, I’m struck by the other numbers below.  The passing stats have weak to almost non-exisitent correlation to points scored and the rushing stats all have negative correlations.

Clemson Correlations

If you think about it, the negative correlation to rushing numbers makes sense – for Clemson.  While the rushing game is important, the Tigers are much more efficient at passing and plays spent rushing decrease the overall efficiency of the offense (yards per play) even if the rushing plays are successful.

Running plays are obviously an important part of the offense and the analysis above made no distinction between a passing play when behind by 10 or a rushing play when ahead by 10.  Perhaps that is something I can develop at some point – analyzing these numbers by game situation.

The data also confirms what we learned in Tuesday’s post (total yards matter) and refines the findings for Clemson – Total yards (no matter how they are gained) and plays run are two key stats for the Tiger offense.

Winning Percentage by Stat for 2011

Below you’ll find a graph that shows the winning percentages of teams that were better in the categories listed than their opponent.  For example, the team that had more rushes won 71.51% of the time in 2011.

The highest percentage on the graph is yards per pass, not yards per rush or total rushing yards as one would think.  This data covered 713 games between Division I opponents during the 2011 season (including conference championships and Bowl Games).

You can find the traditional numerical summary including averages for each category here.

Some of these make perfect sense (losers tend to throw more passes) and some others less so –  having less penalty yards is not that important, for example.

This is just the beginning of a long-term look at these stats.  We’ll keep adding to the database as the 2012 season progresses to see what trends are holding constant and which are changing.

Do Yards Matter?

Over the last few years I’ve noticed multiple web sites, blogs, and other publications state their case as to why total yards gained don’t matter. The usual argument goes something like this: “It doesn’t matter how you score, as long as you score. A team doesn’t get any yards for scoring on defense or special teams, so yards aren’t important – scoring is”.

While that statement is true, at least to a point, the real answer is of course yards matter. Gaining yards does not guarantee points, but it sure increases the odds of scoring. Sure teams score in all kinds of ways every year, some of them not involving offense. But the vast majority of the time touchdowns are scored by offenses and the way offenses score is by gaining yards. It may be a few yards or it may be a lot of yards, but the offense has to gain yards in the large majority of cases for the team to score.

Just because it’s not a one-to-one relationship or a relationship that can be easily defined (i.e. 400 yards = 30 points, for example), doesn’t mean that yards aren’t important.

If you need further evidence that yards matter, the chart below will help clarify the relationship between yards gained (total offense) and scoring. 8 of the top 11 scoring teams are in the top 10 in total offense (total yards gained) and 9 of the top 10 in total offense are in the top 13 in scoring. That’s not a coincidence.

Team Total Offense Scoring Offense
Houston 1 1
Baylor 2 6
Oklahoma State 3 2
Oklahoma 4 10
Nevada 5 31
Oregon 6 3
Texas A&M 7 11
Toledo 8 8
Boise State 9 7
Northern Illinois 10 13

 

There are absolutely outliers and exceptions to this rule, but that doesn’t mean that yards don’t matter statistically speaking. Naysayers can point to a game or perhaps even a team, such as LSU, where yards really don’t matter, but those are few and far in between.

Still not convinced? Even with all of their defense and Tyrann Mathieu seemingly returning a fumble or punt every week LSU still scored 86% of their touchdowns on offense and all of those involved gaining some number of yards. For all of the talk about Oklahoma State’s “opportunistic” defense, 93% of their touchdowns were scored on offense. 94% of Clemson’s touchdowns were scored on offense.

The point is that in the vast majority of cases (90%+) touchdowns are scored by the offense and the only way for an offense to score a touchdown is to gain yards.

Yes, yards matter.