Motion-blurred skater in a Calgary Flames sweater

Breakdown · BOS at CGY

Flames edge the Bruins in overtime

Final / OTMon, Dec 29

The verdict · stolen

The Flames stole one. They lost the expected-goals battle 2.61–2.28 and won anyway.

BOS 1 · CGY 2

◆ By the ModelJul 11, 10:22 PMxG: xgboost-0.758Edited for clarityDrafted from NHL play-by-play by Backcheck's model, worded for clarity by an AI editor that may not change a number. Nobody at Backcheck was at the rink. How this works

The Bruins had the better game on paper. Expected goals split 2.28–2.61 in Boston's favor—the underlying play suggested a Bruins victory. Instead, Calgary won 2-1 in overtime. D. Wolf made 25 saves at 0.962 SV%, outperforming expected goals by 1.61. The Bruins underperformed their xG by exactly 1.61 goals, a difference nearly matched by Wolf's goaltending excellence.

Connor Zary scored from the doorstep at 01:53 of overtime to supply the game-winner, but the story was set before then. Calgary held 45% of shot attempts (21–26 on goal), translating volume into high-danger looks: they generated 3 and buried 2 through crashing the net effectively. Boston also created 3 high-danger chances but converted none—costly in a one-goal game. J. Swayman (BOS) kept the Bruins close with a 0.950 SV% and 1.28 goals above expected, but Wolf's theft made the difference.

The breakdown in twelve frames

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Every number is from this page

Final · OT · Dec 29

BOS

CGY

Flames edge the Bruins in overtime

Chances 2.6 – 2.3Did they deserve it? →

Did they deserve it?

Dead even on chances. The Flames took it anyway.

Expected goals · chance value

BOS

2.61

CGY

2.28

53% of the chances47%

The board read BOS 1, CGY 2. The chances read BOS 2.6, CGY 2.3.

Our xG model · NHL play-by-play · all situations

Luck check

CGY

−0.3

goals above expected

CGY2.28 expected · 2 scored

Expected

Scored

BOS2.61 expected · 1 scored

Expected

Scored

The Bruins left 1.6 goals on the table against what their chances were worth.

PDO = sh% + sv% · drifts to 1.000 over a season

Every goal, in order

P1 18:06BOSA. Peeke1–0
P2 13:32CGYB. Coleman1–1
OT 01:53CGYC. ZaryPP1–2

NHL play-by-play · chance value from our xG model

Where the shots came from

BOS

36 shots

Final

67 shots

CGY

31 shots

BOS CGY GoalBigger dot · more dangerous look

shots · 1 in

shots · 2 in

Every unblocked shot · press play to replay it

Chances by danger

BOSCGY

0 / 3

0.92 xG

High danger

0 / 2

0.53 xG

0 / 9

1.05 xG

Medium

1 / 13

1.31 xG

1 / 38

0.64 xG

Low

1 / 34

0.44 xG

The Bruins went 0 for 3 from the slot.

Danger tiers by our xG model · high ≥ 20% chance

In the net

D. Wolf

+1.6

CGY · 25/26

B+

J. Swayman

+1.3

BOS · 19/20

The numbers, checked

BACKCHECK

Flames edge the Bruins in overtime

A model, not a newsroom. Every number on these frames comes from the NHL's play-by-play and our own models. Nothing was watched, guessed or heard from anyone.

Read the full breakdown

backcheckreport.com

01 / 08 · Final

Every goal, in order

How it happened

NHL play-by-play

1stshots 9–8

18:06BOSA. Peeke(M. Lohrei, S. Kuraly)1–0

2ndshots 7–9

13:32CGYB. Coleman(M. Backlund, J. Hanley)1–1

3rdshots 8–1no goals

OTshots 2–3

01:53CGYC. Zarypower play1–2

score reads BOS–CGY

Source · NHL play-by-play (api-web.nhle.com)

Process vs result

The numbers

XGBoost xG · NHL play-by-play

2.28

CGY chances

Goals their shots were worth

−0.3

Finishing

Goals below what those chances were worth

1.021

CGY puck luck

Above 1.000 — the bounces went their way

49.5%

Shot attempts

Under half — they were outshot

Split by club

Who controlled the game

2.61Expected goals2.28

BOS 53% of the chance quality

26Shots on goal21

3High-danger chances2

50All attempts (Corsi)49

Adjusted for score: BOS 50% · CGY 50%

Faceoffs · CGY won64%off38%neu47%def

Source · NHL play-by-play · XGBoost xG

How the game was won

The danger ladder

shotsgoalsexpected

High dangerslot & crease

BOS0 / 3 · 0.92 xG

CGY0 / 2 · 0.53 xG

Medium dangermid-range

BOS0 / 9 · 1.05 xG

CGY1 / 13 · 1.31 xG

Low dangerperimeter & point

BOS1 / 38 · 0.64 xG

CGY1 / 34 · 0.44 xG

BOS went 0-for-9 from medium danger on 1.05 expected goals — 1.1 left on the table.

Source · Backcheck xG model · NHL play-by-play

The luck layer

Finishing vs expected

expectedactual

BOS

1 G · 2.61 xG · -1.6

CGY

2 G · 2.28 xG · -0.3

0123

BOS finished -1.6 against expected, CGY -0.3.

Source · Backcheck xG model

Shot types · rush and rebound chancesopen +

What they shot — and what went in

Shot diet

goalsshots

BOS

WRIST0/21

SLAP0/6

SNAP0/4

BACKHAND0/1

TIP IN0/2

DEFLECTED1/2

OTHER0/14

CGY

WRIST1/11

SLAP0/6

SNAP0/6

BACKHAND0/4

TIP IN0/2

DEFLECTED0/1

OTHER1/19

BOS

CGY

Off the rush

1 G on 19

1.58 xG

1 G on 18

1.41 xG

Off rebounds

0 G on 3

0.54 xG

1 G on 3

0.34 xG

Wrist shots carried the volume: BOS went 0-for-21, CGY 1-for-11.

Source · Backcheck xG model · NHL shot types

New to these numbers?

Two things happened in this game: who created the better chances, and who put the puck in the net. They are not the same thing, and this page separates them on purpose.

The one to watch is expected goals— the best single read on who deserved to win. When it disagrees with the scoreboard, that disagreement is usually the story. Nothing here is a projection; every figure is computed from this game's play-by-play. Full glossary →

xG: Expected goals. Every shot scored by how often that exact look goes in. 2.5 xG means the chances were worth about two and a half goals.
HD: High-danger chances — shots from the slot and the crease, where shots actually become goals.
Corsi: Every shot attempt, including the ones that missed or got blocked. A rough read on who had the puck.
Adj.: Score-adjusted. Teams that trail shoot more and teams that lead sit back, so this corrects the attempt count for the scoreboard.
GSAx: Goals saved above expected. A positive number means the goalie stopped more than an average goalie would have on those shots.
PDO: Shooting % plus save % — a luck gauge. It sits near 1.000 over a season, so a game far from it usually means the bounces decided it.

Shot by shot

In the net

Graded on goals saved above expected

J. Swayman

BOS · 19/20 · .950

+1.3

saved above expected

B+

the night

By dangerG/attxGsaved

High danger0/20.5+0.5

Medium1/131.3+0.3

Low1/340.4-0.6

A+ ≥ +2.5 saved above expected · A ≥ +1.5 · B+ ≥ +0.75 · B ≥ +0.25 · C ≥ −0.25 · D ≥ −0.75 · F below −1.5

D. Wolf

CGY · 25/26 · .962

+1.6

saved above expected

the night

By dangerG/attxGsaved

High danger0/30.9+0.9

Medium0/91.1+1.1

Low1/380.6-0.4

A+ ≥ +2.5 saved above expected · A ≥ +1.5 · B+ ≥ +0.75 · B ≥ +0.25 · C ≥ −0.25 · D ≥ −0.75 · F below −1.5

67 shots · press play to watch the game back

Where the shots came from

NHL play-by-play coordinates

BOS

36 shots

Final

67 shots

CGY

31 shots

BOS CGY GoalBigger dot · more dangerous look

Each club shoots toward its own end — BOS left, CGY right — the way you would watch it. A dot's size is how dangerous the look was, from distance and angle; it is a proxy for shot quality, not the xG model the article is written from. Hover a dot for the shooter and the clock.

Ranked from the box score

Three stars

Points first

Three stars · computed, not voted

B. Coleman

#20 · L · CGY

1 G · 0 A · 4 SOG · 18:22 on ice · +1

A. Peeke

#26 · D · BOS

1 G · 0 A · 2 SOG · 17:56 on ice · +1

M. Backlund

#11 · C · CGY

0 G · 1 A · 2 SOG · 16:38 on ice · +1

Ranked from the box score — points first · Backcheck

What the model said beforehand

Before the game

Written Mon, Dec 29

Open the pre-game read

Written from the numbers

The read

Edited for clarity

◆ By the ModelJul 11, 10:20 PMEdited for clarityDrafted from NHL play-by-play by Backcheck's model, worded for clarity by an AI editor that may not change a number. Nobody at Backcheck was at the rink. How this works

The model projects a 2.5–2.6 expected-goal game with Calgary at 52% win probability. This is a pick'em.

The Flames are the hotter team. They're 7-3-0 in their last 10 games, a run that projects toward playoff contention. Boston is minus-6 in goal differential over the same span—a signpost of deeper trouble. Yet the underlying metrics tell a different story: both teams own 47.0% expected-goals share and 49.0% Corsi percentages at 5v5. The talent is matched. The separation is luck. Calgary's 0.985 PDO reveals cold finishing and due-for-positive regression. Boston's 1.023 PDO cuts the opposite way: the Bruins are running hot and should expect natural erosion.

Both goalies face back-to-back starts. D. Wolf for Boston, J. Korpisalo for Calgary. Watch for either a backup or a weary starter.

Viktor Arvidsson is Boston's engine at 1.04 expected goals per 60 minutes, with 18 goals and 24 assists. His 13.0% shooting rate is real—he's not on a lucky streak. Tanner Jeannot supplies 6 goals and 14 assists at 0.75 xG/60. Calgary counters with Blake Coleman at 0.89 xG/60, 16 goals, and 12 assists. Matt Coronato adds 10 goals and 16 assists at 0.80 xG/60.

Boston's Elias Lindholm and Calgary's Coronato are defensive weak links. Both teams have converted just 0% of their goals from hard chances and rebounds—a statistical anomaly that will almost certainly regress.

The model calls it even because the talent is even. Calgary's form advantage is real, but Boston's luck should normalize and its underlying metrics remain strong.

What the model said beforehand

The model's lean

CGY 52%

52%

CGY

Model favorite

48%

52%

BOS50CGY

CGY by 4 points of win probability — effectively a coin flip. Projected score BOS 2.5–2.6 CGY; 18% chance it's tied after 60.

Source · Backcheck Poisson projection · season scoring rates

Season rates · 5v5

Tale of the tape

NHL stats API · our xG

BOS← edge

edge →CGY

47.0%47.0%

49.0%49.0%

2.392.36

2.672.66

2.221.76

1.822.15

1.0230.985

The season numbers split 3–3 — no clear process edge — and the luck row (1.023 vs 0.985) says BOS has been getting the bounces, which tends not to last.

Source · NHL stats API + our xG · 5v5

Form · Last 10

BOS

4-5-1

-6 GD · 1d rest

CGY

7-3-0

+7 GD · 1d rest

1.023

BOS PDO

Luck gauge · drifts to 1.000

0.985

CGY PDO

Luck gauge · drifts to 1.000

What decides it

Keys to the game

Regression watch

The Flames' PDO is 0.985 — running cold, due for positive regression.
The Bruins' PDO is 1.023 — running hot, expect some regression.

Things to watch

D. Wolf is on a back-to-back — watch for a backup start or a tired starter.
J. Korpisalo is on a back-to-back — watch for a backup start or a tired starter.
The Flames are the hotter team by points pace (7-3-0 in their last 10).
The Bruins are underwater at -6 goal differential over their last 10.
The Flames' PDO is 0.985 — running cold, due for positive regression.

Last game's lineup · confirmed at warm-up

Lineups

NHL box score

BOS

Expected in goal

J. Korpisalo

back-to-back.909 last start

Backup Jeremy Swayman · +28.8 GSAx this season

Back-to-back: the backup often gets this one. Treat the starter as unconfirmed.

No completed game on file for this club yet.

CGY

Expected in goal

D. Wolf

back-to-back.935 last start

Backup Dustin Wolf · -1.8 GSAx this season

Back-to-back: the backup often gets this one. Treat the starter as unconfirmed.

No completed game on file for this club yet.

Lineups are the players who dressed in each club's last game, with their minutes; clubs confirm tonight's at warm-up. Every player this preview names was in that lineup.

Computed danger · scouting

Players to watch

NHL stats API · our xG

BOS

Viktor Arvidsson18G 24A

1.04 xG/60 · 2 HD · 13.0% sh

Tanner Jeannot6G 14A

0.75 xG/60 · 2 HD · 8.3% sh

CGY

Blake Coleman16G 12A

0.89 xG/60 · 2 HD · 11.4% sh

Matt Coronato10G 16A

0.80 xG/60 · 0 HD · 6.6% sh

Keep going

Where to next

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