Hope springs eternal: turnover margin and regression to the mean

Jerry Hinnen gets my schwiing! award this morning, for this post on a subject near and dear to my heart – regression to the mean.  It’s a fun read (even if it’s filtered through an Auburn perspective) and at least you’ll know where I stole the idea from when I do something similar on a really slow news day in July.

For the post you’re reading, though, I’m changing the focus to look at one narrow area – turnover margin – filtered through the lens of the entire conference, to draw some conclusions about why this should matter if you’re a Dawg fan.

There are two reasons why t/o margin and regression to the mean are significant.  The first is that t/o margin, by and large, is generally not a consistent matter.  As Jerry puts it,

… With certain exceptions (almost all of which are named “Pick-Prone Quarterback”), turnover margin appears to be almost entirely random and sees huge fluctuations year-to-year.

If you want specific evidence of that, here’s a chart of SEC turnover margin by team for the years 2002-2009.

2009 2008 2007 2006 2005 2004 2003 2002
Alabama 19 6 4 7 8 6 1 15
Arkansas 15 -9 4 -4 -1 -3 11 14
Auburn 1 -8 0 5 -3 4 1 9
Florida 7 22 5 5 18 4 7 -9
Georgia -16 -3 9 -1 11 -2 11 8
Kentucky 2 5 -1 15 -9 -2 -1 -17
LSU 4 -1 20 0 -9 -2 5 -1
Ole Miss -7 -2 -10 -3 -5 -3 6 5
Miss. St. -5 -4 0 -5 2 -1 -21 -15
S. Carolina -4 -11 -7 -2 2 1 7 -5
Tennessee 3 2 7 0 -7 6 3 2
Vanderbilt 3 9 -2 -2 -2 4 -10 -14

There’s only one team on that chart that’s managed to stay in the black every season – Alabama.  Similarly, there’s only one team that’s finished in the black only one time – Mississippi State.  Most of the story there is one of random fluctuation.

The second reason this matters is because when it comes to wins and losses, turnover margin is kind of a big deal.  Back in 2008, Matt Hinton took a look at a variety of statistical categories to measure their relationships to won-loss records and found a significant correlation between turnover margin and winning.

… Offensively, we see that the best teams were far more efficient that they were necessarily explosive: turnover margin, passing efficiency and third down percentage correlated to better records at the top and worse records at the bottom than even total offense, and to much better/worse results at the poles than rushing or passing yards per game; even an essentially ancillary number like time of possession showed a greater correlation to success than yardage in either category…

So, it’s somewhat random and it matters.  It’s not like a head coach can game plan a season by saying that he’ll have his team go plus-nine in turnover margin; however, if you’re faced with managing a quarterback derby, it’s probably wise  to insist on going with the hand that’s the least Coxian, all other things being relatively equal.

Nonetheless, there are a few observations worth drawing from that chart worth noting.

  • While it’s possible to play in the SECCG without having a positive t/o margin, it’s highly unlikely.  In fact, in that eight-year period, it only happened twice – ’06 Arkansas and ’05 LSU.  Both of those teams lost.
  • On the flip side, every SECCG during that time had at least one participant that finished in the top two in the conference in t/o margin.
  • There’s been only one season out of those eight when there wasn’t a team with a turnover margin in double digits, either plus or minus (2004).  But it’s not as if many teams generate big t/o margin numbers in a given year.  The most double-digit tallies to have occurred in one season was four five, in 2002.
  • That being said, no team with a positive double-digit margin finished with a losing record in those eight years.  Three teams (’02 UK, ’08 S. Car. and ’09 UG) out of eight with negative double-digit margins won more games than they lost in that time.

Oh yeah, that minus-16 from last year’s Georgia team, there are a few things you can say about that.  The first, and most obvious, is what an anomaly it was in comparison with the other seven years.  During that stretch, Georgia had never gone through a season with a lower t/o margin than minus-three.

For more context about how unusual that number was, look at the range each SEC school generated between its best and its worst years, first, from 02-08…

  • Tennessee – 13
  • Alabama – 14
  • Georgia – 14
  • Mississippi – 16
  • Auburn – 17
  • South Carolina – 18
  • Mississippi State – 23
  • Vanderbilt – 23
  • Arkansas – 26
  • LSU – 29
  • Florida – 31
  • Kentucky – 32

… and then compare that to the chart including the 2009 results…

  • Tennessee – 13
  • Mississippi – 16
  • Auburn – 17
  • Alabama – 18
  • South Carolina – 18
  • Mississippi State – 23
  • Vanderbilt – 23
  • Arkansas – 26
  • Georgia – 27
  • LSU – 29
  • Florida – 31
  • Kentucky – 32

… Georgia dropped from having the second narrowest range to the eighth.  Making things even worse, all three of the teams with bigger ranges did so with much higher plus years than Georgia’s best (+11 in 2003 and 2005).

Not good, in other words.  Except for one silver lining – if you’re convinced about the effect of regression to the mean, it’s hard to see how Georgia repeats the results in 2010.  That last year’s number is so out of the mainstream (for Georgia, at least) suggests that the probability of a more favorable result this season is even likelier.  That can’t hurt.

Also, Steele.


UPDATE: I almost forgot to mention that there’s some great work on turnover margin at College Football Resource that covers an earlier period (with some overlap) than the above data.  Here’s the SEC breakdown from 1998-2006.

And just for a hoot, check out Southern Cal’s numbers over the same period.  The last three years?  2, 7 and 0.  If you’re looking for a reason for USC’s drop off in dominance, that’s a pretty good place to start.


UPDATE #2: Jerry checks out my chart and comes up with a nifty observation.

… Here’s what jumps out at me: from ‘02 to ‘08 eight teams had margins greater than or equal to either +15 or  -15, and seven of those saw their margin swing by a minimum of 13 turnovers the following season. (2003 MSU is the sole exception.) Average swing for those seven teams? 16.4.

What kind of record would you foresee for Georgia this season if the Dawgs merely broke even on turnovers?


Filed under Stats Geek!

19 responses to “Hope springs eternal: turnover margin and regression to the mean

  1. OnTap

    Firstly, on the preceding post….this is By Damn America and if you’ve worked your butt off and anyone has a problem with a couple of ads to put a little money in your pocket….they are Commies…or Nazi’s…..or both.

    Secondly, on this post…I know this sounds crazy, but that -16 and having a record of 8-5 actually, in a weird way, shows just how much talent that team had on it. Most any other team that gave up the ball that many times and took it away so few times would’ve had zero chance to have even a winning record. The fact we beat a few teams with a 0-3 and 1-3 TO margin says those guys could overcome a lot of bad stuff happening.


    • Throw in the strength of schedule (CBS 14th; Sagarin 7th) and it’s even more remarkable.


    • The Realist

      Yes. The 2009 team could have easily been a 10-win team. Think about Kentucky. They pissed that game away with turnovers at the goalline, in UK’s territory, etc. LSU came down to two plays at the end (1 – not covering a kickoff… 2 – giving up a 30 yard touchdown run). If Georgia holds in those two scenarios, they go 10-3 and have the fans have a much different outlook on last season’s results and this season’s prospects…

      Of course, it may have saved Willie’s job, so I’m not necessarily grousing about how things turned out. Sometimes it is better to have to endure a little pain to have a better quality of life for the long haul.


  2. Hogbody Spradlin

    The 1980 national champions had a phenomenal turnover ratio. Somebody check me on this but I recall hearing +33.


  3. JasonC

    The only team that had a horrible t/o margin and actually got worse was Miss St in 02-03, so there is hope that regression to the means will occur.


  4. kevin

    Hey Sen,
    I count 5 in 02.

    Also, UF has been pretty consistent in the black the past 7 years. UF, in fact, is up about 17 (total) vs. UA in that time frame


  5. Pete

    Is it just me, or did the teams with the most takeaways in the SEC win the MNC the last 4 years?


    • Dawgaholic

      Can’t agree with everyone that turnovers are basically random. While I agree that 1/3 to 1/2 of turnovers are random (batted balls, helmet to ball hits, etc.), many turnovers are the direct result of controllable factors. These include pressure on the QB, DBs having the ability to catch the ball, fumble prone RBs, defensive players attempting to strip the ball, and playcalling/audibles.

      These factors can be coached and learned with experience. (Generally speaking, younger RBs fumble more and younger QBs pick correct audibles less often.)

      I must therefore contend that teams are very likely to end up in a certain range of the turnover margin area depending on their coaching, talent, and experience. I’d suspect that if you looked at the lucky break turnovers, you’d be hard pressed to find a team that ended up in double digits either way and most teams would be between +5 and -5 for each season.


  6. Amen Brother! Turnover margin should be at the very top of the Dawgs “get better or uh-oh” list!


  7. FJ

    “Offensively, we see that the best teams were far more efficient that they were necessarily explosive.”

    I STRONGLY agree with this statement. IMO one the most impressive attributes that Florida and Alabama shared the last couple of years is that a 3rd and 3 was almost automatic.


  8. Will Trane

    Turnovers…football, turnovers…basketball, errors…baseball, all comes down to how mentally and physically tough you are. You can create turnovers on defense with being in the right position with speed and strength and understanding the schemes. Same in football and basketball. In baseball you eliminate the errors, recorded or unrecorded.

    I read Coach Perno’s comments about the Diamond Dawgs after Saturday’s no show. They are young, but how young do you have to be to understand this. Or if you are an underclassmen, grad, or whatever. There is this ironclad rule.

    “If you keep making the same mistake, guess what? You get the same damn mistake again.”

    You do not have to be a freaking genius to understand that. You can do the drills and be coached until hell freezes over. But somewhere you have to get mentally tough in sports! It does not matter what D1 program you are in.

    Coach Perno has a good idea what a team looks like. It ain’t there, yet. Frustrated? Perhaps, and who can blame him. Some of this guys made some sublte moves over the weekend. Look at Carson Schilling. I think he made some moves.

    But you can not face three batters, put three on via walks and hit batsman, two wild pitches, in the first inning. That will not cut it any league. No more than you can get a penalty after a TD puts you ahead in the closing seconds, and line up to deep behind the kickoff. How long do you have to play, drill, and practice not to have those kind of mistakes.

    Each player must come with the mental toughness to play each play!

    Run the numbers, they are only the products of the play.


  9. Joe

    Not sure this has been pointed out but our worst seasons and seasons where we underperformed we had a negative TO ratio.


  10. shane#1

    Turnover ratio and special teams mistakes, including turnovers, were the two main reasons for UGA’s lackluster 2009 season. Throw in a rather dismal pass defense and it’s a wonder the Dawgs made a bowl game. Some of the turnovers were by relatively inexperenced offensive players, some by true freshmen, so there is hope of correcting that problem. The lack of takeaways was due to three problems. 1- Lack of QB pressures. QBs commit most turnovers, but any decent Div 1 QB will make good decisions when he isn’t pressed. Stress ceates mistakes, mistakes create turnovers. 2- Tacklers that have not been taught to swipe at the ball. I don’t recall seeing a single UGA player trying to dislodge a football last year. 3- DBs not being taught to make a play for, or even to look for the ball. 4- D linemen and LBs simply not being alert when there was a fumble. How many times did we see UGA players looking lost at sea while the offense recovered their own fumble? FUMBLE DRILLS people! Fumble drills, fumble drills, fumble drills! And while you are at it, throw in some tip drills for the DBs!


  11. It would be interesting to see this put into a certain amount of context as well, particularly in light of the statement regarding low turnovers not necessarily correlating to offensive explosiveness. For example, Alabama was on the successful end of turnover margins, but it factors both offense and defense. It’s true that the Tide didn’t turn the ball over much as a part of it’s ball-control style offense of running heavily and not really testing the secondary often in the passing game. But the converse of that is that Alabama led the SEC in interceptions made, which is at least partly a matter of playing with a lead most of the season, which often led to opponents forced to put the ball in the air more often. As a league, the SEC made 171 interceptions compared to only 99 fumbles recovered. That doesn’t dismiss the more variable nature of the fumble, but it does point to a little more importance to the more controllable nature of the turnover in the passing game.


  12. shane#1

    tidefan, true, a good running game forces the opponent to pass more often thus increasing the chance for an int. However, I think in UGA’s case there was simply not enough stress placed on creating the turnover. Some breaks are simply lucky breaks, most breaks are created by being prepared and by hard work.


    • I would agree with that. That’s why I point out the disparity in fumbles recovered to picks league wide. Fumbles can more easily be attributed to luck. But interceptions — while not without a luck factor themselves — are more often a function of the defense’s play. Getting to the QB seems to be the strongest. There was a loose correlation last season between sacks and interceptions but not sacks and forced fumbles.
      Of the teams that finished in the top half of the league in fumbles recovered last season, only one lost fewer than five games (Ole Miss, who lost four). In terms of interceptions, though, the two best records in the league led the league in picks and the four best records all tied for sixth or better in the league.
      That’s the part that likely isn’t going to see a lot of regression to the mean. The real number that would indicate Georgia should enjoy an improvement isn’t represented here. It’s 18. That’s the number of times UGA’s opponents put the ball on the turf. The Dawgs only covered two of those.



    If you are going to talk about UGA football Offense, what should be said sir is that Coach Richt told all his offensive coaching staff he is taking over the offense.

    If you are going to talk about UGA football Offense, then put up the offensive numbers.

    For the 1st 5 years of the Coach Richt Era Coach Richt did very well.

    For the next 5 years including this year up-coming, we face stark contrasts. I base this on Aaron Murray for the up-coming season but what it absolutely has shown the last 4 years is :

    21 fumbles a year every year on the average last 4 years

    14 interceptions a year every year on the average last 4 years

    # 96 NCAA in Penalties on the average called against us every year of the last 4 years

    The rest of T/O is defense. We have a fine, if not 1 of our best Defenses the last 30 years this up-coming season and feature the 2 best kickers on any team in America, both All-America kickers this season.

    Instead of missing the boat in the discussion, if you are going to talk about UGA football Offense the last 4 years heading into this season with 2 freshmen quarterbacks, what we have is an utter failure of the UGA Offensive Coaching Staff.

    Or else Coach Richt would not have agreed with me and demoted them all and taken over their former responsibilities 3 weeks ago now.


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