2012 Turnover Analysis Updated Thru Alabama

Submitted by Enjoy Life on September 4th, 2012 at 12:54 PM

Preseason Prediction (Obviously made before the game): Michigan will end the year with a +8 Turnover Margin (TOM) or better (2011 was +7). Fumble recovery rates which were excellent last year (77% for takeaway and 65% for giveaway) will be closer to the average of 50%. BUT, very good teams have good TOM and M is a very good team this year. In addition, DRob will significantly reduce his interceptions thrown and the experience in the secondary will increase interceptions gained.

Random?: ZooWolverine did an excellent post on the Year-To-Year Correlation of Turnovers. I agree with the conclusions that year-to-year correlation is poor. But, that does not indicate that turnovers themselves are random. I have been analyzing TOs since 2009 (with data going back to 1998 for all FBS teams) and have concluded that TOs are a reflection of the performance of each team (good teams will have better TOMs than poor teams). So, if you had a poor team last year (2010 for M) and a very good team the next year (2011 for M) there should not be a correlation of TOM from year to year. My prediction  for TOM for M for this year is based on the prediction that M will be a very good team again this year and is not based on the actual TOM of last year. (Very good teams will have a TOM of +5 or better.)

Uh, yea: Hysterical conclusion is that M is on track for a TOM of –26 for the year! A more reasonable conclusion is that any analysis of anything based on a single game is just silly. My analysis of turnovers has led me to the conclusion that TOs are not random – instead, TOs are a reflection of the relative performance of the teams playing the game. It is obvious that Alabama was a much better team than M and therefore I would expect that Alabama would also win to TO battle.

Synopsis for Turnovers: M ended the game with a TOM of -2. This was a strange game because there were 2 meaningless TOs. Gordon recovered a fumble forced by Taylor on the last play of the half and Bellomy threw his first interception with 1:26 left in the game. These offset each other and did not distort the TOM. Both TOs by M were interceptions by DRob. Whoever decided it was a good game plan to have Denard go back and throw the ball as high and as far as he could (he had actually regressed last year on passes over 15 yards) must have been smoking something.

imageSynopsis for Expected Point (EP) Analysis: TOs obviously did not impact which team won the game but TOs did significantly impact the margin of victory. imageWithout TOs, M would have lost by approximately 19 points instead of 27. I always thought Michigan would have to play their best game in the Hoke era and end up with a +2 TOM to win this game.

(See the Section on Gory Details below for how the adjustment for Expected Points (EP) is calculated.)

imageNational Rankings: It's only one game so don't get too excited or too panicked.  All rankings are from TeamRankings except for forced fumbles which is from CFBStats. imageThe four columns with *** show the best correlation to offense and defense (per Advanced NFL stats).

The Gory Details

Details for Turnovers: Here is overall summary for all games by player (data in yellow was affected by this week's game).


Expected Point (EP) Analysis: Basically, the probability of scoring depends on the line of scrimmage for the offense. Therefore, the impact of a TO also depends on the yard line where the TO is lost and the yard line where the TO is gained. Each turnover may result in an immediate lost opportunity for the team committing the TO and a potential gain in field position by the opponent. Both of these components can vary dramatically based upon the down when the TO occurred, the yards the TO is returned, and whether the TO was a fumble or an interception.

Here are the details for the game.


The analysis is a bit tricky because: (A) the TO may directly result in lost EP for the offense but (B) only modifies the EP for the team gaining the TO because the team gaining the TO would have gotten another possession even without the TO (due to a punt, KO after a TD, KO after a field goal, etc.). The Net EP Gain must take into account the potential EP gain without the TO. The EP gain without the turnover is based on where the field position would have been for the next possession if the TO had not occurred.

Take a look at DRob's second interception. It was 3-9. Therefore, even if the TO had not occurred (i.e. the pass was incomplete), M would still have given up possession on the next play because they would have punted. The result is that M did not lose any EP. Alabama ran the interception back for a TD and obviously gained 7 EP. But, Alabama would have gotten the ball anyway and would have had a chance to score. Based on a net punt of 36 yards, Alabama would have gotten the ball at the M45 which results in 3.07 EP. Thus, the net EP gain for Alabama is 3.93 and the net differential is 3.93 EP.

If it had been 2-9, M would not have necessarily given up the ball (they still had 3rd down to make a first down). In that case, the TO would result in a loss of 1.02 EP (the probability of scoring from your own 3 yard line is fairly low but not zero). And, the net differential in that case would be 4.95 EP.


image_thumb17_thumb_thumb_thumb_thum[2]The expected point calculations are based on data from Brian Fremeau at BCFToys (he also posts at Football Outsiders). Fremeau's data reflects all offensive possessions played in 2007-2011 FBS vs. FBS games. I "smoothed" the actual data.

Here is a summary of the smoothed expected points.