NHL Season Analysis: How Game Metrics Change Over a Season
Quite often I find myself thinking - does the game evolve during regular season? It would make sense that there are less goals towards the end of the season, more penalties in the first months of the season, and so on.
Also one thing that at least I hear quite often, is that youngest players typically have good start to the season, which is followed by less productive period after 20-25 games.
If the game really evolves within a season, that should be visible from the data.
Game statistics
I took the data starting from season 2010-2011 (excluding the seasons 19-20 and 20-21, since they had special schedules), and plotted average numbers from regular season games by game ranges (Games 1-10, 11-20, etc.)
So let's take a look at the results, starting with numbers that stay consistent through the season.
What stays the same
Looks like that amount of goals, shots on goal, blocks, takeaways and average goal difference of game stays fairly consistent, although there seems to be slight decline in blocked shots and increase in takeaways in the last ~10-15 games
Based on the those figures, it seems that in big picture, there are no big differences between different periods of season.
But those are the ones that stay quite consistent through the season. Next, let's see what things have variability withing a season.
What changes during the season
Hits
Starting with hits. There is no any radical difference in amount of hits, but except for the first and last ~10 games, there is slight increase towards the end of the season. Nothing major, but something I wouldn't count as consistent through the season.
Penalties
Amount of penalties is clearly higher in the start of the season, especially during first 10 games. That seems quite significant, since it is ~1.5 penalties per game more than in the end of the season.
There seems to be also slight decline towards the end of the season.
Rest time
Christmas, All stars and Olympic breaks definitely shows up in average rest times between games. As expected, that is followed by quite tight schedule in the last quarter of the season.
Player statistics
About players, what especially interests me is the extremes - young and old players. Both ends might have the same issue, that the longer the season goes, the production suffers. For older individuals, that could be simply due to not being in as good shape as in younger years, and with younger guys, potential reason could be that the long NHL season is something that they are not used to, and therefore the season gets more exhausting towards the end.
But those are just speculations - let's see if we can find supportive evidence from data.
For this purpose, I have selected only cases where player has played more than 70 games during the season. And the season selection remains the same - data is since season 2010-2011, and seasons 19-20 and 20-21 are excluded.
Let's start with comparing point production in different portions of season:
Simply
comparing performance by age, seems like that point production of
players at age 18-20 drops after 20 games. For example, if we compare
points per 60 minutes of ice time games 1-20 and 21-51, point production
of defensemen drops ~11.2%, and point production of forwards drops
~5.9%.
For older players, the results are a bit more mixed. In age group 29-33, there seems to be slight decline in point production until last quarter of the season, and players in age group 34-37 seem to perform better in first half of the season, which would really make sense for older players. Older age groups have a bit more variability in results, which might be due to low amount of players in those groups
Which also raises one important aspect that is good to keep in mind here. The data shows higher point production for players age 18-20 and 40+. It does not mean that best age for a hockey player is under 18-20 or 40. It means that there are not many players in those categories - those players are exceptions, not typical players in the NHL. In addition to high points, it is also one potential factor for the high variability in results of those age categories.
It seems that there is some variability in point production of defensemen in first season, but based on the data, defensemen seem to have more fluctuation regardless of amount experience in league.
However, the data from forwards seems to be quite consistent, even in the first season.
So, young age might cause the inconsistency, rather than lack of previous NHL experience. If that is the case, we should see that when comparing how players in different ages perform in their first season, and if the players in same age group, but with more experience, have more consistent performance.
To find out that, I compared point production of five different categories:
- Age 20 or under, playing first season
- Age 20 or under, after first season
- Age 21-22, playing first season
- Age 21-22, after first season
- Age 23-28, playing first season
It really seems that age is the relevant factor causing variability in performance, not previous experience in league. In older ages, the point production is quite consistent through the season, even in first season.
Summary
In big picture, seems that the game stays fairly consistent through the season.
However, some thing seem to have variability during season - most notably, schedule is very tight in the last quarter of the season, first games have lots of penalties.
About player performance, it seems that in general, defensemen have more variability in point production, while forwards have more consistent performance.
It also appears that young forwards (aged 20 or younger) experience a slight decline in point production after 10–20 games, while players aged 21–22 show relatively consistent production, regardless of whether it is their first season or not. However, it is important to note that the sample size in the younger group (20 or under) is quite small, making the results more susceptible to variability
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