Wednesday, November 7, 2012

The Turnover Index - Week 10

Here are the Turnover Index numbers for Week 10 of the NFL season.  The purpose of these weekly posts is to find betting opportunities by exploiting the market's tendency to overvalue a team's season to date defensive turnovers when evaluating future performance.  See here and here for more background.

The Bears - 28 Turnovers in 8 Games

Before getting to the Week 10 numbers, I wanted to take a look at the Bears and their impressive turnover performance thus far this season.  In their first 8 games, the Bears have generated (received?) 28 defensive turnovers.  Going back to 1998, only the 2005 Bengals managed more turnovers (29) in the same amount of time.  See the table below for the outcomes for all teams that managed at least 24 defensive turnovers in their first 8 games:


TurnoversWin-LossAt the Spread (ATS)
TeamGms 1-8Gms 9-16Gms 1-8Gms 9-16Gms 1-8Gms 9-16
2005 Bengals 29 15 6-2 5-3 4-3-1 4-4-0
2012 Bears 28 ??? 7-1 ??? 5-2-1 ???
2002 Packers 27 18 7-1 5-3 4-4-0 4-4-0
2003 Chiefs 27 10 8-0 5-3 7-1-0 3-5-0
2000 Lions 26 16 5-3 4-4 5-3-0 4-4-0
1998 Cardinals 25 14 4-4 5-3 4-4-0 1-6-1
2000 Ravens 25 24 5-3 7-1 5-3-0 6-2-0
2006 Ravens 25 17 6-2 7-1 5-3-0 5-3-0
1999 Seahawks 24 12 6-2 3-5 4-4-0 2-6-0
2001 Jets 24 15 5-3 5-3 4-4-0 4-4-0
2005 Giants 24 13 6-2 5-3 6-2-0 5-3-0
2006 Bears 24 28 7-1 6-2 5-3-0 4-2-2
2007 Lions 24 11 6-2 1-7 5-2-1 1-6-1
2009 Saints 24 23 8-0 5-3 6-2-0 2-6-0
Total 25.1 15.4 79-25 63-41 64-38-2 45-55-4

The first thing to notice are the average defensive turnovers for the second half of the season.  As expected, there is significant regression to the mean.  Teams average about 1.6 turnovers per game, so one would expect about 13 turnovers over an 8 game span, on average.

Also note the performance against the spread.  As expected, these teams did very well against the spread in the first half of the season, but that performance flips for the second half of the season.  This is consistent with what I found in my original post on turnover differential: the betting market tends to over-correct for what is (mostly) un-repeatable turnover performance.

Week 9 Results

So, how did the Turnover Index do in Week 9?  It correctly picked Pittsburgh to cover the spread against the Giants, but missed (badly) on the Bears-Titans game, where it expected the Titans to cover.

Turnover Index Through Week 9 (ATS): 5-3-0


Week 10 Picks


  • NY Giants @ Cincinnati - Cincinatti has had 15 fewer defensive turnovers than the Giants, so we would expect Cincinnati to cover as a four point home underdog
  • Houston @ Chicago - I have a feeling that the Bears and Giants are going to be weekly fixtures here until they start regressing to the mean.  The Texans have had 14 fewer defensive turnovers than the Bears, so we would expect the Texans to cover.
Here is the complete list:

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