Blitzing the Odds: Expect a Third Elite MSU Defense?

It was much more likely that the dominating defense of 2011 would take a step back, than a step forward. Yes, the unit returned almost all of its starters and backups, and the coaches were all the same, and yet...

Creating a single elite defensive unit is surprisingly easy. 5 out of 11 'longtime' Big Ten members have cracked the top 15 in the country in yards per play against in the past 6 years, 6 of 12 if we include 2010 Nebraska BTN-style, and 8 of 14 if we throw in future members Rutgers and Maryland.

Compounding on that success is tougher. Only about a quarter to a third of the teams who manage this top 15 finish are able to repeat within the next two years. But Michigan State was one of the few, and with that rite of passage comes a new-found respekt.

Respekt (Bill C.):

Considering the linebacking corps should be every bit as well-equipped to help in the passing game as it was last year, and considering the pass rush already wasn't that great, I again don't see why the Spartans should expect to slip much. This should once again be a top-five defense all around...

Respekt (Phil Steele):

"Michigan State's got the best defense in the Big Ten -- yes, even better than Ohio State," Steele said. "They'll have it once again this season."

Respekt (Drew Sharp, whose troll game is impeccable):

The defense might be better than last year’s unit that kept those losses an inch close.

On and on you could dig up quotes like this. People might have no idea what to make of the offense, but almost everyone is really really comfortable that MSU is going to put out one of the top-10, 15, defensive units in the country. And hey! Feels good man, I'm not gonna lie. But I think it's a valid exercise to slow down expectations on the defensive side of the ball a little bit. Because if it's tough to put out back-to-back elite defenses, going back-to-back-to-back is also challenging, possibly even tougher.

A short list. A really short list.

We'll look at defensive effectiveness in this case through two different lenses. First, we'll use the standard efficiency metric yards per play, or YPP, (total yards / total plays). For the purposes of this column, I'm considering an elite defense to be within the top 15 in the country. Because a few of these YPP numbers had ties at spot #15, some years contain 16 or 17 teams instead of 15. We'll be looking at the past six years broken up into four 3-year chunks.

Table:

Turning those numbers to names, we can look at who's been most successful.

Three years in a row: Alabama, Florida, Clemson, Penn State, Ohio State, TCU, Texas (Alabama and Florida have each pulled off a three peat 3 separate times, while OSU has done it twice.)

Two years out of three: Florida State, Boise State, LSU, Michigan State, South Carolina, South Florida, Oregon, Nebraska, Utah, Iowa, Boston College, Virginia Tech, USC

One year: Bowling Green, BYU, Connecticut, Fresno State, Northern Illinois, Rutgers, Stanford, Utah State, Southern Mississippi, Arkansas State, Illinois, West Virginia, Texas A&M, Vanderbilt, Georgia, Maryland, Kent State, Syracuse, Temple, Pittsburgh, North Carolina, Oklahoma, Tennessee, California, Troy, Kansas, Oregon State, Auburn, UCLA.

Under a framework of Yards Per Play against, how likely is it for a team to build off their previous top-15 defense?

Well, as you can see, recent history says you've got a little bit over a 1 in 4 chance of going from a single year to two top-15 performances within three years. The good news is, that improves to a little better than a 1 in 3 chance when going from a repeat into a threepeat under YPP.

(Note: When a team does something like this: Year one: top 15, Year two: not top 15, Year three: top 15, you get a situation where it's impossible for that team to go from two in a row to three in a row in Year four. How often does this happen? Not often. My quick count was just 5 out of the 30 did it this way rather than back-to-back. So I removed those five from the calculation. This pushes it from a ~30% chance to ~34% chance, so that's why the number looks a little different than expected.)

Better hope in 'advanced' statistics?

As you know, I like the work they do over at Football Outsiders and their ratings systems find way to account for strength of schedule, field position, and garbage time in a way that leads to familiar, and yet different, lists on these sorts of evaluations. What does their F+ rating system have to say about the easy of putting out consecutive elite defenses?

Putting some names to numbers again-

Three years in a row: Alabama, Oregon, LSU, Boise State, Oklahoma, TCU (Alabama and Oklahoma each had three separate threepeats. Boise State did it twice.)

Two years out of three: Notre Dame, Michigan State, Florida State, South Carolina, Rutgers, Texas A&M, Stanford, LSU, Texas, Penn State, Ohio State, Nebraska, Iowa, Clemson, Florida, Boston College,

One year: Oklahoma State, West Virginia, Georgia, Illinois, Utah State, BYU, Missouri, Miami, Auburn, Clemson, Wisconsin, North Carolina, Air Force, USC, Virginia Tech, Wake Forest, Connecticut, California, Oregon State, South Florida, UCLA, Kansas, Michigan.

At a quick glance it's easier to get from one to two, harder to get from two to three. To be more exact:

When fielding a first top-15 defense a little under  two out of every five of those teams will manage the feat again within the next year or two. Unfortunately, unlike under YPP, under F+ a team falls to just a one in four chance of going from repeat to threepeat..

(In this case, six teams by my count did the year one, year three thing and were removed from the 'two in a row to three in a row' calculation).

Conclusion

Recent history says MSU's defense has a 66%-75% chance of failing to achieve a top-15 unit again in 2013.

Of course, recent history isn't everything. As it did in the flip from 2011 to 2012, the Spartan defensive unit returns many key starters, enviable depth, and a experienced and cohesive coaching staff. But the findings here indicate that a drop into the top 25, or top 40, or worse, would not be as unlikely as they might first seem.

As we hope for, and expect, improvement from a shaky offensive output from 2012, it's worth considering whether the defense can maintain such a high level of play for the third straight year, and whether we are too quick to assume so. If they do, they'll join some elite company. But if they don't, they'll join many others who couldn't quite get there.