HOW THE GAME GRADE WORKS
The Game Grade rates one player's night in one game, from 0 to 10. It is really three numbers: Production is what the score sheet says he did, Impact is how play went while he was on the ice, and the Game Grade itself is the blend of the two.
We show both halves because they disagree often, and the disagreement is the interesting part. A player can pick up two assists on a night his line was hemmed in its own end. Another can drive play all game and leave with nothing on the score sheet. One number would hide both stories.
What the numbers mean
The scale is set so that an ordinary NHL game lands in the sixes. The bands mean the same thing every night, for every position:
The method
Every ingredient is measured in goals above average for the position: what he did, minus what an average forward or defenceman does in the same ice time, multiplied by what that thing is worth in goals. The ingredients simply add up. That is a deliberate choice — it means every player page can show exactly what raised and lowered his number, and it means we can publish the formula.
Each of the two totals is then turned into a 0–10 rating by asking where it sits among every game played at that position over the last two NHL seasons, regular season and playoffs. That comparison set is frozen. If it were refitted every night, last week's 8.2 would quietly drift, and “his fourth-best game of the season” would reshuffle by itself.
Production: the score sheet
What each event is worth, in goals, before comparing with the positional average:
A secondary assist is worth about half a primary one, an empty-net goal a third of a real one, and faceoffs barely count. Those are the three places ratings like this most often go wrong: they reward points so heavily that the rating becomes the points column again, and they let centres pile up credit by taking forty draws.
Impact: how play went
Impact is built from expected goals — every shot attempt weighted by how likely it was to go in — rather than from the goals that happened to be scored while he was out there. Over one game, on-ice goals are mostly luck; chances are much less so.
| Ingredient | Forwards | Defence |
|---|---|---|
| His own scoring chances (expected goals) | 0.50 | 0.35 |
| Chances his team created with him on the ice, even strength | 0.55 | 0.45 |
| Chances allowed with him on the ice, even strength | −0.55 | −0.80 |
| High-danger chances, for minus against | 0.03 | 0.04 |
| Power-play chances created | 0.30 | 0.25 |
| Penalty-kill chances allowed | −0.30 | −0.40 |
| Tough assignments (per even-strength minute, per point of competition quality above 50) | — | 0.015 |
Defencemen are measured against other defencemen, and chances against weigh more heavily for them than for forwards.
Shutdown defencemen
A defenceman whose job is to face the other team's best line will give up more chances than one who plays sheltered minutes. That is what the job looks like, not a failure at it. We tested the obvious fix — weighing chances against even more — and it made those players rank worse, not better.
What works is crediting the assignment. Defencemen who draw tougher opponents over the season earn a small bonus for every even-strength minute, shown on their page as Tough assignments. One honest limit: it uses the quality of opposition he has faced across the season, not in that single game. The matchup panel on each page shows who he actually played against that night.
Goalies
Goalies are never rated on how many saves they made. A save count rewards facing a lot of weak shots. Production is goals saved above average: what a league-average goalie would have allowed on that many shots, minus what he allowed. Impact is goals saved above expected, which accounts for how dangerous the shots were, plus a small credit for high-danger saves beyond the usual rate. For goalies the blend leans toward Impact, 60 to 40; for skaters it is an even split.
Who gets a rating
A skater needs seven minutes of ice time and a goalie needs twenty. Below that the page still exists, with his score sheet, but there is no number — a rating from four shifts would be noise. During a live game the numbers move as the game goes and settle once it is final.
Preseason games are rated on the same regular-season scale and labelled as exhibition. They are scored against the scale and never added to it, and they never count toward season averages or leaderboards.
What it is not
The Game Grade describes one game. It is not a measure of how good a player is, and one game is a small sample: a great player has plenty of sixes and an ordinary one will have the occasional nine. It also cannot see everything. A smart defensive read that ends a rush before a shot is ever taken leaves no trace in the data. Use it as a well-informed first look, then go read the page underneath it.
To see one, open any game from Scores, go to the box score, and tap the coloured number beside a player's name.
Model version 0.2