Conventional Wisdom says that NHL games are "harder" down the stretch of a long season, and in the playoffs. "Teams are tightening up defensively, battling harder for pucks along the walls and in one-on-one battles, and playing simpler, smarter games", is how one NYPost writer summarized it. Late-season games are often characterized by references to "playoff-like" hockey - meaning tight-checking, hard-hitting, and intense. Speaking about the the playoffs, Mike Babcock said: "It's important for your players to be able to watch on TV just how hard everyone plays and how little room there is and how the game works.'' [The linked Stephen Whyno article is a treasure trove of playoff-hockey cliches]. And for NYR fans specifically, there have been a lot of good articles written on the physical play in their first round series against the Canadiens, which include Conventional Wisdom type quotes.
Is it true? Are late season games harder to play? Are they more physical? Are they tougher defensively? And how do those games compare to playoff games themselves?
One way to look at this is to see if games become tighter, more defensive, harder to play, or more physical as the season progress, and then into the playoffs. Personally I think it's hard to specifically isolate what makes a game "tight" or "hard to play", but I think many people would look to things like hits, shots on goal and goals, and players blocking shots, as evidence of how "hard" a game was.
I went to NHL.com and pulled every team's regular season and playoff game from 2007 to the end of the end of the 2016/17 season, using it's custom search option for hits, blocks, shots, and faceoffs (these are all collected in one search, along with giveaways and takeaways). I then went to Corsica.hockey and got a list of every team's regular season and playoff games from the same period to get the TOI figure (since that's not included in the NHL options). Unfortunately I had to use NHL.com for the primary data here, since Corsica does not allow you to include "hits" as an option in a per-game custom search (yet?), and no other fancystats site has a game-by-game search option. Putting this data together manually took a long time.
Then I sliced each team's data into 4 regular season "quarters" and the playoffs. Since the NHL plays an 82-game regular season, the quarters aren't equal - Q1 is actually 21 games, Q2 the next 20, Q3 the next 20, and Q4 the last 21. I then adjusted the numbers to a "per 60" rate stat, to account for OT games. [Note: for whatever reason, some games were missing from the downloaded search results - it is only a handful of games over the course of 10 seasons, and there are still over 22,000 regular season games, and 1,400 playoff games in the data, so I'm not worrying about it.]
So here are the results:
What do we see (remember these are per team):
- There is no appreciable difference in early season results and late season results, in any of these categories, and certainly no significant "increase" in these metrics in the last segment.
- Hits: there is an ~33% increase between regular season hits ("All RS") and playoff ("PO") hits (~8 hits for per 60 minutes). This could be a result of players being more willing to throw hits, and it could also a result of the teams involved in the playoffs, or (more likely in my opinion) both. [I don't think "scorer bias" would change in the playoffs, but I guess that's possible as well].
- Blocks: there is an ~10% increase between regular season blocks and playoff blocks. It's something, I guess, but 1 block per game per team doesn't seem significant to me.
- Faceoffs: there are ~3 more faceoffs per 60 in the playoffs. I wonder if games get "sloppier" in the later minutes of a playoff game, especially in longer OT games, but I don't have the skill using play-by-play files to figure it out.
- Shots: there is no real difference in actual shots on goal between the regular season and playoffs. An average NHL team gets around 30 shots on goal per 60 minutes, regardless.
- Goals For and Shooting % were included in the NHL search option, so I left them in. It's no surprise to me that the playoff results are consistent with the regular season. People may think scoring in the playoffs is "harder", but it's pretty damn hard in the regular season too.
So what difference does it make?
Obviously this is very high level, and, to some extent, results will be weighted by the teams that have been successful over this 10-year period (the top 5 teams in playoff games played account for 34% of the total playoff games). I also think there might be ways to help examine how "tight" or "hard" a game is to play that we don't accurately measure right now. For example - how much of a game is spent in a one-on-one (or multi-man) battle for possession? I also didn't look at penalties (not because I didn't think it would be interesting, but because I didn't think to look until well after I had started working with the data files).
Overall, though, I think Conventional Wisdom is mostly wrong. While playoff games might have some more hitting than a regular season game - in pretty much every other way that Conventional Wisdom might suggest is important, regular season games do not become "harder" as the season goes on, and the playoff games are not "harder" than the regular season games.
...Again I'm right in my analysis.