As I've been watching the playoff games this season, it seemed like the refs were calling a lot more penalties this year than previously. Traditionally the referees have been known for letting the teams play and only calling penalties when they have been egregious (i.e. no blood no foul). Apparently that has changed for this playoff season and in a significant way.
I looked at only the first 8 playoff games in the first round from this season and the previous two seasons. I also excluded any obvious penalties that refs have to call (e.g. boarding, delay of game, fighting, roughing). As you can see in the chart above there have been more penalties called in the first 8 games of this season's playoffs than in either of the previous two seasons. There has been approximately a 40% increase in the number of penalties called during the first 8 games this season than last season. This has equates to 6.25 penalties called per game this year compared to only 4.9 and 4.7 from the previous two seasons respectively. Essentially the refs have been calling an extra penalty per game compared to previous two seasons.
The heat map is the list of penalties I included in this analysis and how many were called during the first 8 games of the playoffs. Hooking and interference were the two most common both this season and last season. However, there has been a 50% increase in the number of those penalties called. Tripping and slashing are the next two common this season. Last season, it was cross checking and holding that were 3rd and 4th on the list. There has been a 50% decrease in the number of those penalties called from last season's playoffs to this year's games.
So in case you were wondering, you are not imaging it. The refs are calling more penalties at the start of the playoffs this year than they have in the past. I think it has made for more boring hockey. It also gives the refs more influence in the outcome of the game and that doesn't make for good hockey in my opinion.