Synopsis: There have been literally thousands of posts about the decline in Michigan's offense and the improvement of the defense this year. After 10 games, some of the raw numbers are staggering. Michigan's defense has allowed 52% fewer points per game and the offense is scoring 14% fewer points per game. There were also literally thousands of posts debating what effect the tempo offense had on both offense and defense. If we had tried to create an experiment to answer these questions, we probably could not have done as well as the comparison we now have between 2011 and 2010.
To provide valid comparisons, it is necessary to make two adjustments; (1) Delete the impact of the OT game in 2010 – both points and plays, and (2) adjust for turnovers in 2011 and 2010. After these adjustments, we can incorporate tempo by calculating points per play. Here are the results.
As you can see, after adjusting for tempo and turnovers, Michigan's offense is actually scoring more points per play this year as compared to last year. And, after those same adjustments, about 55% of the improvement in defense can be attributed to tempo and turnovers. Of that 55%, approximately 18% is due to tempo and 37% is due to turnovers.
Michigan's offense has had 12% fewer plays this year and the defense has had been on the field for 16% fewer plays. This is primarily due to the tempo of the offense. There can be no doubt that the tempo of the offense was a significant reason for poorer performance of the defense in 2010.
BTW, turnovers are NOT primarily a matter of just luck but are a result of better performance. Better performing offenses will have fewer turnovers, better performing defenses will force more turnovers. And, these turnovers help make the offense and defense even better.
A Look At The Numbers: A direct comparison of raw data from 2011 and 2010 is simply not valid. The most common error is a failure to recognize the impact of a 3 OT game in 2010. This added 22 points to the offense and 20 points against the defense. This is approximately a 6% increase.
In order to determine the impact of turnovers, I already had the numbers from 2011 because of my weekly turnover analysis. But, I had to go back to 2010 and calculate all the expected points for each turnover of each game. This was not a pleasant experience as I had to relive the catastrophe of 27 giveaways and only 18 takeaways (over 10 games).
Each turnover usually results in a loss of expected points to the team losing the TO and, usually a gain in expected points to the team gaining the TO. In most cases, the loss in expected points is greater than the gain. Unless a team has no turnovers, the net result is that both teams lose points. The team with fewer turnovers simply loses fewer points.
In 2010 Michigan's offense lost 22 turnovers thru 10 games and the defense had only 15 takeaways. Without the TOs, M would have scored 31 more points and the opponents would have scored 18 more points.
This year M has lost 19 turnovers but the defense has had 23 takeaways. Without the TOs, M would have scored 15 more points this year and the opponents would have scored 50 more points.
Why The Difference In Expected Points?: The expected points for each TO are calculated based on the down, spot TO was lost, and spot TO was gained. The maximum value for a turnover is 11.7 EP (1-10 at the 1 yard line and the TO is returned for a TD), and the minimum is –1.2 (4th down on the 40 and the pass is intercepted on the 1 yard line – ball should have been knocked down and team would have taken over at the 40). This year, M had a TO worth 11.03 EP (Heron's return from the M04 for a TD) and another TO worth –0.53 (interception by EMU on a 4-5 from the V34 that resulted in EMU getting the ball at the V27).
In addition to the turnover margin, several other reasons the EP are significantly different between 2011 and 2010 are:
1. M has 3 returns for TD this year – none in 2010.
2. Opponents have lost 6 TOs in the red zone this year – just 3 in 2010.
3. M has 5 fumbles lost and 14 interceptions this year – 10 fumbles lost and 12 interceptions in 2010 (fumbles have greater impact).
4. Opponents have lost 16 fumbles and 7 interceptions this year – 6 fumbles and 9 interceptions in 2010 (fumbles have greater impact).