Hockey Analytics 101

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Any shot attempts made by a player over the duration of a game. It tracks every shot attempt, whether it hits the net, misses, or gets blocked. More attempts = more possession = more control of the game.

Corsi’s inverse, which tracks any shot attempt allowed by a team for players on the ice. Lower CA = stronger defensive performance. 

Not all shots are created equal. Expected Goals (xG) is like asking, “What are the odds this shot is going in?” A shot from the slot with little traffic in front? High xG. A lazy flick from the blue line? Not so much.

Defense matters, and xGA is the flip side of xG. It measures how likely the shots against your team are to become goals. It’s a great way to see how well your defense and goalie are keeping opponents’ quality chances at bay.

Take your expected goals for, subtract your expected goals against, and you’ve got xGD. If it’s positive, you’re generating more quality chances than you’re giving up. 

Fenwick is Corsi’s refined cousin—just a little more sophisticated because it doesn’t count blocked shots. It’s a cleaner measure of offensive pressure. For example, we’ve seen breakaways result from defenseman blindly drilling pucks into the opposing forwards shin pads. While Corsi views this as a positive, Fenwick does not. 

How much better is this player than someone you'd call up from the AHL? GAR answers that question, providing insight to overall player value against a replacement level player.

For goalies, GSAx is their badge of honor (or shame). It tells you how many goals they’ve stopped compared to the number of goals you’d expect based on shot quality. If a goalie’s GSAx is high, they’re standing on their head. 

Think of this as your luck meter. It’s used to measure the sum of a team's shooting percentage and save percentage when a particular player is on the ice. The idea behind PDO is to quantify "luck" or variability in performance by combining these two stats. If it’s way above 1000, keep the pregame rituals the same. If it’s below 1000, you're probably due for a turnaround.

Points Per 60 tells you how many points a player puts up for every 60 minutes they’re on the ice. This is helpful when comparing someone playing 10 minutes a game to someone playing 20.

A derivative of P/60, PPP/60 shows how many points a player collects for every 60 minutes of power-play time. It is the sum of PPG/60 and PPA/60. A player with a high PPP/60 is making opponents pay for their trips to the penalty box while collecting a lot of daps from the bench.

PKGA/60 measures how many goals a team gives up while down a player, over 60 minutes. This metric gives insight into penalty kill efficiency; the lower, the better.

A metric that tracks the quality of the defensemen a forward faces or the quality of the forward a defenseman faces when on the ice.

A metric that tracks the quality of teammates that are on the ice at the same time as the player in question.

RAPM is a metric designed to evaluate skater performance while accounting for factors beyond a player's control, such as teammates, opponents, zone starts, and game situations. By using ridge regression, RAPM simultaneously controls for these variables, providing a more accurate assessment of a player's offensive and defensive contributions. This approach improves on traditional on-ice metrics by isolating a player's individual impact, offering a clearer picture of their performance across different game conditions and strength states.

Converting Corsi into a percentage form. This entails finding the ratio of on-ice events for a team or player compared to the opposition they faced. Relative Corsi tells you how well a player’s driving possession when they’re on the ice compared to when they’re riding the pine. 

TOI is just how much time a player spends on the ice. Ice time matters. A player with more ice time is being asked to do more. In hockey analytics, we need to adjust for ice time differentials through the use of rate/60 minute statistics.

WAR translates GAR into wins. By converting goals to wins, we can adjust the overall GAR values to account for each season’s goal scoring environment. At the end of the day, winning is what matters. WAR tells us how much a player has contributed to their team in a format that directly corresponds to winning.

Ever wondered if a player makes their linemate better or if they’re just riding shotgun? If you skate alongside McDavid and Draisaitl, you are one lucky winger. WOWY compares a player’s performance when paired with a teammate vs. when they’re separated.

Not all shifts start equally. Zone Starts tell you how often a player starts in the offensive, neutral, or defensive zone. Why is this important? Nic Dowd starts ~30% of his shifts in the defensive zone; his role is to move the puck up the ice. Nathan MacKinnon starts ~23% of his shifts in the offensive zone–his metrics look different. Pay attention to these details.