NHL fans have now started to kick their statistics knowledge into gear when evaluating players in the modern-day league. NHL statistics can consist of base numbers, charts, or even fancy visuals. Some of the best NHL statistics can be found online. Evolving-Hockey, Moneypuck.com, and Hockeyviz are some of the best websites for NHL data. They focus on a variety of stats, but goals for per 60 is one of the best out there.
The Best Of NHL Statistics: Goals for per 60
The RAPM Chart
One of the best visuals or statistics to use when evaluating a player is a RAPM chart. The RAPM chart was created by Evolving Hockey on June 7th, 2018. RAPM stands for Regularized Adjusted Plus-Minus, which is utilized as a common way to evaluate NHL players. The chart consists of five even-strength statistics (GF/60, xGF/60, CF/60, xGA/60, CA/60) and three power-play statistics (GF/60, xGF/60, CF/60.)
The RAPM chart can sometimes be misleading due to the size and colour of the bars. One may ask, what do those blue and red bars mean? The RAPM chart uses Z-scores to grade and compare players by position. The numbers (1,2,3, etc.) shown on the side of the chart is not raw data, rather how far away a player’s stat is from the mean. All of the data that goes into a RAPM chart are “On-Ice” stats, so the creator (Evolving-Hockey) needed to include other stats in order to create a fair grading system for the charts.
Factors of the RAPM
To isolate every single player’s RAPM impact, statistical proof is needed in order to show how player’s impacts vary from one another. The specific stats that factor into the calculation include score stats, competition, strength stats, back-to-back games, and teammate stats. That data plugged into the RAPM chart is called RTSS (play-by-play) data. RTSS data consists of a combination including the event’s players, where the event occurred, and the goalies in between the pipes.
Stats of the RAPM
To start off, GF/60 (goals for per 60) is the most important stat on the RAPM. This measures how effective a player is at causing goals to be scored. Next, xGF/60 (expected goals for per 60) measures the quality of offence generated by a player. Furthermore, CF/60 (Corsi for per 60) measures how many shot attempts are taken (shots on goal, blocked shots, missed shots.) All of these stats measure a player’s offensive isolated impact at even strength.
Continuing, there are two defensive stats involved in the RAPM chart. The most important defensive stat is xGA/60 (expected goals against per 60.) This stat measures how easy a player makes their goalies job. Essentially, xGA/60 has a lot to do with the quality of shots as opposed to the quantity. The RAPM chart doesn’t use GA/60 (goals against per 60) because the stats is heavily influenced by the goalie’s performance. The second defensive stat used in the RAPM chart is CA/60 (Corsi against per 60.) CA/60 measures how good a player is at preventing opponents shot attempts. A shot attempt consists of shots on goal, missed shots, and blocked shots.
The RAPM also provides power play statistics for players. The power play section of the RAPM chart includes GF/60 (goals for per 60), xGF/60 (expected goals per 60), and CF/60 (Corsi for per 60.) The three statistics are the same as the even-strength metrics, just adjusted to power-play results.
Bell Curve
The bell curve is defined as a common distribution for a variable. Common distribution is also known as the normal distribution. Furthermore, 95 percent of NHL players lie between 2 and -2 SDs from the mean at 0. To put this into perspective, let’s just say Auston Matthews‘ GF/60 is exactly 3 SDs. When Matthews is on the ice, he causes goals to be scored at a rate of 3 standard deviations above average. Due to the fact Matthews’ Z-score is exactly 3, this places him in the 99th percentile of forwards among the NHL when causing goals to be scored.
The Golden Stat
Now, let’s move into the golden stat of the RAPM chart. GF/60 (goals for per 60) is measuring how effective a player is at causing goals for his team per 60 minutes of ice time. Stats on the RAPM chart are adjusted to 60 minutes because every player gets a different amount of ice. This would make the grading process unfair to a player that gets 6 minutes a night as opposed to 25 minutes.
GF/60 is the most important stat because it’s using real goals as opposed to expected goals. GF/60 has a direct impact on the game and it’s much easier to gain cumulative value from offence than it is from defence. Although defence is a great stat, it can have a major flaw in a player’s defensive impact. This is because RTSS data tracks approximately 70-80 percent, making expected goals not perfect. This can plummet a player’s xGA/60, causing it to not be as impactive as GF/60.
However, with GF/60 the only player that’s relied on in the calculation is the player being evaluated. GF/60 is a pure statistic, not focusing on the quality of offence. It’s sort of like the pure result. GF/60 includes the luck factored into the game, while xGF/60 eliminates luck to identify the quality of offence. Unlike xGF/60, the play has already happened, because it’s the score sheet result. With xGF/60 the play is being measured based on the quality of offence. This leaves GF/60 as the most reliable stat, as it can provide the most isolated and individual impact of a player.
Potential Flaws
There are still other factors to take into account with GF/60. For example, viewing who the specific player plays alongside and how high their shooting percentages are. This allows an analyst to know how repeatable their GF/60 statistic is. GF/60 can also vary widely for defenders due to on-ice shooting percentage. Another issue is an analyst can’t isolate one player from another player when they play together for a large percentage of time.
Something to watch for is the “Blue Bar Illusion,” which means that an analyst may think a player is having a strong season due to a high xGF/60, CF/60, and CA/60. However, the player could have a low GF/60 and xGA/60 which can lead to inaccurate analysis.
Conclusion
In conclusion, the RAPM chart is a great way to evaluate a player’s isolated impact. The chart is not perfect, but it’s a fantastic visual to help break down a player’s value. It’s important to use other statistics like OFF (total value of offence), DEF (total value of defence), and WAR (wins above replacement) in your analysis. When evaluated properly, the RAPM can be one of the most useful tools, including GF/60 being one of the most useful stats.
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