enCYCLONEpedia: Defense, turnovers, & optimism(?!?!)

Sep 24, 2016; Ames, IA, USA; Iowa State Cyclones defensive back Brian Peavy (10) intercepts a pass in front of San Jose State Spartans wide receiver Tre Hartley (13) at Jack Trice Stadium. Mandatory Credit: Reese Strickland-USA TODAY Sports

In football, turnovers are probably more random than most realize or are willing to admit. Sure, the defense can facilitate turnovers often with pressure on the quarterback, getting a hand up at the line of scrimmage, or a simple strip of the ball carrier. But fluke bounces of the ball, accidental tips on passes, or any other stroke of luck also fuels turnovers.

I have long had the premise that for Iowa State to have a good defense they very much need turnovers to make that happen. So, I set out to prove my hypothesis.

But there are two front and center problems to proving this out; the natural randomness and luck involved with turnovers and the natural impact that eliminating opponent’s offensive possessions will very obviously limit scoring by removing chances to score. Similarly, a team forcing an increased number of punts would have a better scoring defense, “thank you very much Captain Obvious.”

I started by looking at the numbers on a season level to compare turnovers gained to scoring by points per possession. I have possession data back to 2005 and in those 12 Iowa State seasons the correlation coefficient returned a value of -0.6990. Simply, as turnovers go up opponent points per possession goes down.

But as stated, that is expected so the question is, how does that compare to the rest of the FBS? In the same time span all FBS teams returned a correlation coefficient value of -0.4917.

There seems to be something there that shows Iowa State is more reliant on turnovers to keep scoring down, but that is also very likely related to the fact that Iowa State generally sends out defenses that rank in the bottom third of FBS.

From a different angle, a more anecdotal one, it appears that Iowa State’s defense doesn’t necessarily prevent scoring by earning more turnovers but if the scoring is down it is likely heavily helped by turnovers.

The CFB Analytics ratings archive goes back to 2005, a tempo free and scoring efficiency metric that is adjusted for strength of schedule, in that time Iowa State has had a defensive scoring efficiency in the top half of FBS teams four times; #26 in 2005, #27 in 2012, #40 in 2009, and #53 in 2011. Of those seasons, those defenses had the 1st, 5th, 2nd, and 6th best Cyclone defenses, respectively, for creating takeaways in that time frame. The 2005 and 2009 teams were sixth and fourth nationally in turnover percentage.

But then there are seasons like 2008 where the Cyclones had their third best turnover percentage in the last 12 seasons, and were 22nd nationally, but had a defensive scoring efficiency of 112th (not a lot of punts forced that season).

It isn’t a requirement for the best Iowa State defenses to cause a bazillion turnovers, but almost. That is at least the direction that the data is pointing but not sufficient to say that it is unequivocally true. But, I do think it means that way when you marry the data to what my eyes have seen in the last 12 seasons.

In 2016, the Cyclone defense caused turnovers on just 8.3 percent of opponent possessions, which was good for 110th in the country and showed through with just the 77th best scoring defense. Last year’s defense struggled, and struggled mightily against the run. They couldn’t create turnovers often enough with skill or fortune, which can be an equalizer on the defensive side of the ball.

The looming question for 2017 is if the defense will be able to slow the run but also, can they create enough turnovers? Or, will they be fortunate enough to have enough turnovers fall in their lap?

Reasons for optimism

I’ve probably said and written this one hundred or so times but Iowa State’s performances were so abysmal in the first two (and third game at TCU to an extent as well) that they tarnished the entire season’s ratings numbers. It was that bad. Cataclysmic horridness.

But, you need proof?

In last season’s ratings at CFB Analytics the Cyclones finished 75th in the country with an offensive efficiency of 2.11 points per possession (60th) and a defensive efficiency of 2.57 points per possession (77th).

But, what if you remove the first three games of the season that went so, so terri-bad?

In the last nine games of the season the Cyclones had an offensive efficiency of 2.53 points per possession (would be 30th) and the defense chimes in at 2.36 points per possession (would have been 59th). Those values would culminate in an overall rating of 41st in the country.

Read that again, this 3-9 team performed at the level of nearly a top 40 team in the final nine games of the season. There are questions for this season but there are a lot of returning pieces to a team that made great strides in 2016.

Now, they need to turn those close losses into big wins.