Enough time has passed to evaluate the effect of Bill Belichick's cheating. The cheating took place from 2000-2006, and was ended early in 2007, giving 5 years of data since.
The known cheating consisted of two components, as revealed by Eric Mangini. First, the Patriots would tape opponents defensive hand signals. This permitted coaches to correlate the signals with the defensive alignments and figure out what each signal meant. Second, the Patriots used unregistered radio frequencies, so that the second time they played that team the offensive coordinator could watch the defensive signals and choose the perfect play to tell the quarterback. Normally, the referee cuts the registered radio frequency 15 seconds before the snap, so the offensive coordinator cannot communicate with the quarterback after the defense makes its substitutions, but the Patriots were the only team in the league that had radio equipment that could broadcast on multiple frequencies simultaneously. After the referee would cut the registered frequency, the quarterback could still hear the coordinator on the other frequency, so he could be told the defensive alignment he was facing and what play to call.
So the plays and blocking schemes were always perfect ones to exploit each defensive alignment.
To measure the effect of this scheme, we need to isolate pairs of games in which the Patriots would be obtaining tape then using it. Some teams are played only every three years, so that data is not likely to show much. Teams in the same division are played twice every year and tape from the previous year can be used, so the effect of the cheating scheme may be harder to detect. I started by analyzing games played in the same season against out-of-division opponents. The second game against such an opponent is always a postseason game, so this has the advantage of measuring postseason success. After looking at these games, I saw that the Patriots have twice faced a division opponent (Jets) in the postseason, so I added those games, too. So the analysis below is of all opponents the Patriots played in the regular season and postseason of the same year. There are 30 such games.
The overall result is that during the spying era, the Patriots were 4-5 during the regular season but went 6-2 against the same teams in the postseason, so they did much better the second time. Since the cheating was ended, the Patriots have gone 5-2 in the regular season but dropped to 2-4 in the postseason, with their offense per game dropping by 10 points in the postseason, so they are doing much worse the second time, and primarily because their offense is tanking. This is despite the Patriot offense scoring more points per game during 2007-2011 than they did in 2000-2006, which reflects they have more talent.
The numbers indicate that the cheating scheme was worth more than a touchdown a game.
Results of Patriots' games, showing only opponents they played both in regular season and postseason:
After cheating was ended:
|2011||Denver Broncos||W 41-23 (Away, week 15)||W 45-10|
|New York Giants||L 20-24 (Home, week 9)||L 17-21|
|2010||New York Jets||L 14-28 (Away, week 2)||L 21-28|
|New York Jets||W 45-3 (Home, week 13)|
|2009||Baltimore Ravens||W 27-21 (Home, week 4)||L 14-33|
|2007||San Diego Chargers||W 38-14 (Home, week 2)||W 21-12|
|New York Giants||W 38-35 (Away, week 17)||L 14-17 (Superbowl)|
|Points Scored per Game;||31.9||22.0|
|Points Allowed per Game||21.1||20.2|
|2006||New York Jets||W 24-17 (Away, week 2)||W 37-16|
|New York Jets||L 14-17 (Home, week 10)|
|Indianapolis Colts||L 20-27 (Home, week 9)||L 34-38|
|2005||Denver Broncos||L 20-28 (Away, week 6)||L 13-27|
|2004||Indianapolis Colts||W 27-24 (Home, week 1)||W 20-3|
|Pittsburgh Steelers||L 20-34 (Away, week 8)||W 41-27|
|2003||Tennessee Titans||W 38-30 (Home, week 5)||W 17-14 (Superbowl)|
|Indianapolis Colts||W 38-34 (Away, week 13)||W 24-17|
|2001||St. Louis Rams||L 17-24 (Home, week 10)||W 20-17 (Superbowl)|
|Points Scored per Game;||24.2||25.8|
|Points Allowed per Game||26.1||19.9|