Turnover Analysis Updated Thru Purdue

Submitted by Enjoy Life on November 1st, 2011 at 3:29 PM

Another Non-Fumble: Last week in the post "Turnover Analysis: Fumbles, Forced Fumbles and Backward Passes" I also talked about when a fumble is not a fumble. There was another one in the Purdue game. At 11:36 of the first quarter, it was 1-10 for M on the Purdue 41. DRob dropped the snap, immediately picked it up and started running. In the judgment of the official statistician, this "had no effect on continuing action" and, therefore, is not included as a fumble in the stats.

Synopsis for Turnovers: For the third game this year, Michigan had a negative TOM (-1.0) but won the game (SDSU and NW were the other two). For the year, Michigan has lost 14 TOs (ranked #57) but has gained 20 TOs (ranked #12) for a turnover margin of +6 or 0.75 per game (ranked #18). Michigan is ranked #3 in fumbles lost but is #108 in interceptions thrown. The 14 fumbles recovered is ranked #1 and is the reason the turnover margin is excellent instead of horrible.

DRob had another interception and Gardner had his first interception for the year. DRob now has 11 TD passes and 11 Interceptions. Avery intercepted a Purdue pass to add to this scoop & score in the Minnesota game. There are 17 different defensive players that have either forced a fumble, recovered a fumble, or intercepted a pass.

imageSynopsis for Expected Point (EP) Analysis: Obviously, when the winning team has a negative TOM, turnovers did not impact which team won the game. image

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

National Rankings: Remember the chart and table below includes the WMU game and will NOT be the same as the (incorrect) NCAA Rankings.



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.


image_thumb17_thumb_thumb_thumbThe 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 2007-2010 FBS vs. FBS games. I "smoothed" the actual data.

Here is a summary of the smoothed expected points.



Enjoy Life

November 2nd, 2011 at 11:46 AM ^

When I included expected points (EP) in the analysis this year, I did not realize all of the insight this would bring.

By splitting up the EP lost (due to the loss of a possession) and the EP gained (due only to the difference in field position since the opposing team was going to get another possession anyway), you can see the impact.

M had a 1-10 on the Purdue 39 and lost 3.1 EP

When Purdue intercepted the ball at their own 5 this was worse field postion than would have been expected. Therefore, Purdue actually LOST 0.8 EP becasue of this field position. Usually the opposing team gains EP due to better field position.

The net loss for M was 2.3 EP because no one knew a safety would occur.

You are absolutely correct that the defense immediately reagained 2 points.