January 21, 2019

CFB Trends: Part 6

Other than points, perhaps the most important metric in college football – yards per play. Out of all the metrics I track, none has a higher winning percentage than winning the yards per play advantage over your opponent – not even winning the turnover battle.  The gap has held relatively steady – starting at 1.25 in 2011 and sitting at 1.26 in 2016, though there have been some swings (2013!) along the way.

But again, year in and year out, the fact remains – more plays, more yards and especially more yards per play = winner.

Previously in Series:
CFB Trends Part 1 – Home field advantage?
CFB Trends Part 2 – Vegas knows – favorites win
CFB Trends Part 3 – You’re not imagining it – scoring is up
CFB Trends Part 4 – Everybody runs 70 plays a game
 CFB Trends Part 5 – Yards, yards and yards

Geek Speak: Simple formula for winning 97% of the time


Last week I posted some numbers on how important total yards is as a metric, specifically the importance of gaining more than your opponent. There is one metric that is more important (but it’s close) than total yards: Yards per play. Most coaches track “explosive” plays or “chunk” plays (nod to Dabo) because they are not only momentum changers, they actually often make the difference between winning and losing.

There’s no arguing that since (at least) 2011 there’s a very simple 3 pronged formula for winning (and it’s not “score more points”):

  1. Gain more yards than you allow, and the more the better.  Teams that do this win 78% of the time;
  2. Average more yards per play than your opponent.  Teams that do both 1 and 2 win 86% of the time;
  3. Turn the ball over less than your opponent.  Teams that have done 1, 2 and 3 in the same game have won 97% of the time.

Obviously, winning all three categories is easier said than done, but having a prolific offense gives Clemson a better shot than most at winning and if the Tigers avoid the turnovers that plagued the 2015 squad they will be extremely difficult to beat.

Geek Speak – Yards Per Play (YPP) vs. Total Yards

Much as I did with the total yard metric, I plotted the yard per play (YPP) for the 2,116 FBS vs FBS games for the last three years.

Not surprisingly, the curves and results are nearly the same. In fact, the YPP metric has a slight edge – 79.0% to 77.7%.

YPP Chart and Graph 2014

However, two things stand out to me:

  1. With the exception of the last range, in which both are at 100%, the total yard metric has a higher percentage than the YPP metric in each range. How then does the YPP metric have a higher overall percentage? There are many more (328 to 169) games over the last three ranges in the YPP metric thereby weighting those ranges much heavier.
  2. While the ranges go progressively higher without exception in the total yards metric, it actually goes lower (slightly) from the 3-3.49 range to the 3.50-3.99 range. The sample size is small, only an average of 26 games per year fit in this range, so it’s likely to be an anomaly and will work itself out over time.

There’s not a lot of difference in these metrics in my mind and that was part of my point in the total yard post. YPP is a simple and easy calculation, but you could easily use a metric that doesn’t even require a calculation (total yards) and get similar results.

Final College Football Defensive Efficiency Ratings

Below are our defensive ratings for the 2012 season. There is some interesting information here, some affirmations (Alabama #1 defense), some surprises (Clemson middle of the pack?) and some hilarity (Louisiana Tech was #1 in our offensive ratings, but comes in dead last in the defensive ratings).

These ratings are the reverse mirror image of the offensive ratings, meaning that offensive ratings depend on more plays and more yards per play, the defensive ratings are based on fewer plays run (3 and outs) and less yards per play. On offense the higher the rating the better, while on defense the lower the rating the better.

Similar to the offensive ratings these numbers do not include a strength of schedule component which I believe is an issue and which I intend to correct in 2013. For example, in the ratings below South Carolina and Boise State are exactly tied at #11. But, you would be hard pressed to make me believe that South Carolina, who played Clemson, Georgia and Arkansas didn’t play a tougher schedule (offensively speaking) than Boise.

Some observations from these numbers:

·Three highly rated offensive teams – Arizona, Baylor and Louisiana Tech, pull up the rear in the defensive rankings lending credence to the theory that hurry up, no huddle offenses cause defensive issues for a team.

·On the flip side of that argument, Oregon comes in at 46th, while Texas A&M, Clemson and Oklahoma come in as “average” on defense. Again, I have some work to do on strength of schedule (SoS) to make these ratings a more apples to apples comparison.

·The offensive ratings suggested Clemson faced some bad offenses in 2012, with Auburn, Maryland and Wake among the worst offenses. These numbers also suggest Clemson faced some bad defenses – Duke (108), Ball State (102) and Boston College (101) all ranked in the bottom 20 in defense.

·On the other hand, Clemson also faced 5 top 20 defensive teams – Florida State (2), LSU (8), South Carolina (t-11th), Virginia Tech (18) and Maryland (20).

·Clemson’s defensive rating was very slightly above “average” (average is 100.00). The Tigers gave up a slightly below average number of plays per game (a good thing) and a slightly above average gain per play (not so good).

·Clemson averaged 11.54 more plays per game than its opponents.

·Florida State was the only defense to give up less than 4 yards per play.

·Alabama was #1 in least plays per game allowed and #2 in yards per play given up.

These rankings closely mirror the NCAA’s “Total Defense” rankings – not necessarily a good thing – and my instincts lead me to believe that adding a Strength of Schedule component, as planned, would provide a more realistic picture on both sides of the ball.


dTempo 2012