Did notice the lack of yellow flags this weekend? In the first round of the 2013 playoffs, just 31 penalties were called over four games, a 7.75 per-game average. That’s the lowest per-game average from any week this season, and the 63.25 penalty yards assessed also represent the floor on a per-game basis for any week in 2013.

In 2012, Wild Card weekend was also the least penalized weekend of that season, on both a penalty and penalty yards basis. That is, until the later rounds of the playoffs. As it turns out, these examples are part of a broader trend in the NFL for over a decade.

The graph below shows the average number of penalties called per team game in both the regular season and the postseason going back to 2000. Obviously for 2013, we’re looking at just four games, but for each other postseason, I included all 11 games.

You get a pretty similar picture if you examine the question on a penalty yards basis:

So what’s going on? One interpretation would be that playoff teams are the best teams, and the best teams tend to commit fewer penalties. That would make some sense, but it’s not really the case. From 2000 to 2013, an average of 12.5 penalties per regular season game and 10.5 per game in the playoffs were called. Based on the teams that made the playoffs and the number of games they played, we would have expected 12.2 penalties per playoff game.

So while playoff teams are probably a little bit better at avoiding penalties, that only accounts for about 2% of the 16% decrease we see in penalties in the playoffs. And the difference is even smaller when looking at penalty yards (average during the regular season = 103.4; expected average based on playoff teams in the postseason = 101.7; actual postseason average = 84.9). Last year’s Ravens team was the 2nd most penalized team in the NFL and had the most penalty yards assessed against them in the regular season. After averaging 7.6 penalties and 70 penalty yards per game during the regular season, those averages dropped to 4 and 52 during the playoffs.

If you heard that violent crime was down 16%, you’d probably consider that to be a very good thing. If you dug into the numbers, you might discover that that stat just cited was based on violent criminal convictions, not reported instances of violent crime from victims. That might not bother you very much: after all, you’d assume that we were comparing apples to apples, and if the number of convictions was down from Time X to Time Y, the number of actual instances of crime was probably down over that period, too. If you heard that arrests were also down 16%, you might just think that less violent crime had been committed. Perhaps police enforcement is up, or poverty is down, or certain new policies are achieving their intended effects.

But then you learn that the mayor found the city’s violent crime rate to be a black eye on the city’s reputation. And then you think: just maybe he was so desperate to reduce the violent crime numbers that he told the chief of police that the city should make fewer arrests. After all, fewer arrests results in fewer convictions, and if there were fewer convictions, he could report that violent crime was down. Of course, that wouldn’t be the case at all: saying violent crime is down doesn’t mean that life is better. It just might mean that fewer criminals are being held accountable for their actions. And, in fact, that might mean violent crime was actually on the rise: criminals believing they won’t be punished are more likely to commit crimes. And you might not think that’s a good thing at all.

Apologies for the tangent. What was I talking about again?