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2021 Week 5 · Sun, Oct 10, 2021 · GEHA Field at Arrowhead Stadium
Final
BillsBuffalo38
BY 18final margin
ChiefsKansas City20
Buffalo Bills 38 at Kansas City Chiefs 20. Final.
Chiefs -2.5 upset
The verdict · 2021 Week 5
Buffalo Bills 38, Chiefs 20 — and it was over early.
It turned at Q2 0:02 — 65.7 win-probability points to the Chiefs on one snap, the largest move of the game, and it still was not enough.
The snaps that bent it
The biggest swing of the game · Q2 0:02
Unnamed on the sheet
Chiefs
7-H.Butker kicks 12 yards from KC 35 to KC 47, impetus ends at 50. 46-Jaq.Johnson (didn't try to advance) to KC 47 for no gain.
O 57 ✓
Chiefs closed -2.5 and lost outright — an upset against the closing number.
Buffalo Bills 38–20 — never really in doubt late. Biggest swing: Q2 0:02, Chiefs +65.7% win probability on one snap.
65.7
win-probability points on one snap
The largest move of the game. The two below are drawn against it.
Unnamed on the sheetBillsQ1 4:362-T.Bass kicks 68 yards from BUF 35 to KC -3. 13-B.Pringle to KC 28 for 31 yards (33-S.Neal). FUMBLES (33-S.Neal), RECOVERED by BUF-9-A.Smith at KC 34. Penalty on KC-44-D.O'Daniel, Offensive Holding, declined.
12.4pts
Stefon DiggsBillsQ2 4:56(4:56) (Shotgun) 17-J.Allen pass deep middle to 14-S.Diggs to KC 11 for 61 yards (49-D.Sorensen).
15.9pts
What separated them
Giveaways
Bills won this one — no giveaways, against Chiefs at 4 giveaways.
Billsthe gap went the way the scoreboard did
Every snap
Bills won this one — +0.35 expected points per snap, against Chiefs at -0.16 expected points per snap.
Billsthe gap went the way the scoreboard did
Throwing the ball
Bills won this one — +0.59 expected points per dropback, against Chiefs at -0.08 expected points per dropback.
Billsthe gap went the way the scoreboard did
Running the ball
Bills won this one — +0.02 expected points per carry, against Chiefs at -0.45 expected points per carry.
2 other measures were inside a third of the league's own spread — two clubs doing the same thing, so they are not shown.
2 of the 3 swings name a man the week's roster cannot confirm, so those portraits are withheld.
Drawn from the weekly play-by-play file, which paints on the Monday 4:00 AM ET sync after the game.
The model against the market, the momentum underneath, every drive — scrub to replay it
How the game was won
The model and the market were 1.8 win-probability points apart on the average play, and 6 apart at the widest — with the model the more convinced about Bills.
MarketModelmodel higher on Chiefshigher on Bills178 of 189 plays carry both curves
Q2 · 0:02Bills 24 — Chiefs 13BUF ballBUF 84%
Bills 84%Chiefs 16%
7-H.Butker kicks 12 yards from KC 35 to KC 47, impetus ends at 50. 46-Jaq.Johnson (didn't try to advance) to KC 47 for no gain.
Swing +65.7 for ChiefsExpected points +0.02 for ChiefsThe model had Bills 3 points higher than the market did.play 99
The solid line is the betting market's home win probability; the dashed line is the play-by-play model's. The shaded band between them is the disagreement — emerald where the model liked the home team more, red where it liked the away team more. Drag across the curve or use arrow keys to replay the game; gold diamonds mark the biggest swings.
Highest-leverage plays
2nd · 0:02BUF +66% win prob7-H.Butker kicks 12 yards from KC 35 to KC 47, impetus ends at 50. 46-Jaq.Johnson (didn't try to advance) to KC 47 for no gain.
2nd · 4:56KC +16% win prob(4:56) (Shotgun) 17-J.Allen pass deep middle to 14-S.Diggs to KC 11 for 61 yards (49-D.Sorensen).
1st · 4:36BUF +12% win prob2-T.Bass kicks 68 yards from BUF 35 to KC -3. 13-B.Pringle to KC 28 for 31 yards (33-S.Neal). FUMBLES (33-S.Neal), RECOVERED by BUF-9-A.Smith at KC 34. Penalty on KC-44-D.O'Daniel, Offensive Holding, declined.
3rd · 7:20BUF +12% win prob(7:20) (Shotgun) 15-P.Mahomes pass short left intended for 10-T.Hill INTERCEPTED by 23-M.Hyde at KC 26. 23-M.Hyde for 26 yards, TOUCHDOWN.
2nd · 7:51KC +9% win prob(7:51) (Shotgun) 17-J.Allen pass deep left to 1-E.Sanders for 35 yards, TOUCHDOWN.
2nd · 2:00BUF +8% win prob(2:00) (Shotgun) 15-P.Mahomes pass incomplete deep right to 87-T.Kelce (21-J.Poyer).
SettledThe modelled figures are the league play-by-play model's, not ours.
How the points landed
The margin ledger
Emmanuel Sanders's 35-yard touchdown catch with 7:51 left in the 2nd put Buffalo Bills ahead for good. The lead never changed over the 6 scores that followed.
Lead
1st8:35Harrison Butker·38-yd field goal38-yard field goalholder T.Townsend · snap J.Winchester+30–3
Bills ahead 6–2 on categories, including the biggest gap of the duel — sacks taken.
Expected points added, per play
The centre line is an average play. A bar to the right of it is a side that gained more than the situation was worth; a bar to the left is a side that lost ground. All six bars share one scale, ±0.59 points.
Every snapexpected points added per play, all downs
+0.35Bills: +0.35 expected points added per play
−0.16Chiefs: −0.16 expected points added per play
Dropping backexpected points added per dropback
+0.59Bills: +0.59 expected points added per play
−0.08Chiefs: −0.08 expected points added per play
Running itexpected points added per rush
+0.02Bills: +0.02 expected points added per play
−0.45Chiefs: −0.45 expected points added per play
Neither side “wins” volume or play-calling mix, so neither is drawn as a duel: Bills ran 51 snaps at a 59% dropback rate against Chiefs’s 79 at 80%. Red-zone trips: Bills 5, Chiefs 5.
NoteBills won the down-to-down efficiency fight: 0.35 expected points added per play vs -0.16.
Derived from the play-by-play, no model
The Read
7 of 8 readings cleared their snap floor and were tested against four comparisons: this week's whole slate, the team's own season, the week before, and the team's own ordinary spread. Every bar below is set in that team's own week-to-week swing, never in league points — one team's swing runs 1.6 to 3.1 times the entire league's spread.
highest in the league that weekAgainst the weekTendencies
KC's early-down pass rate, 80.3%, was the highest of the 32 team-games charted in week 5 — 0.8 points clear of the next team along.
Past their previous high of 65.2% in week 1.
A 2.6-swing turn from week 4.
66 early downs this game, floor 15 — 17 of their games behind the ruler, and their own week-to-week swing is 10.9 points.
The season-grain rooms, pointed at this one game
Was this normal for them?
7 of 8 readings cleared their snap floor. Every deviation below is measured in that team's own game-to-game swing, not in league points — because one game's swing runs from 1.6 to 3.1 times the whole league's spread.
their week-to-week swingall 32 teams
upper band = their week-to-week swing · lower rule = all 32 teams · scale -14 pts to 24 pts
inside their normal wobble · −4.4 vs their 15.5%, and they swing ±7.1 week to week (−0.62× that swing) · 63 dropbacks
Chiefs3.3%
leaned — stayed blocked · −9.3 vs their 12.7%, and they swing ±5.4 week to week (−1.72× that swing) · 30 dropbacks
Play-action rate
Charted from 2022. The columns exist for 2021 and are entirely empty, which is not a season of data.
Blitz rate sent
Charted from 2022. The columns exist for 2021 and are entirely empty, which is not a season of data.
NoteKC's sack or hit rate was the night's one real departure: 3.3%, 9.3 points below their season mean of 12.7% and 1.7 times their own 5.4-point weekly swing.
The Game Day Roster
Who was out, who dressed and never took a snap, and who was on the field how much. Game-day list and snap counts from the weekly roster and snap feeds. Practice-squad and injured-reserve players are not shown — they were never on the game-day list.
Buffalo Bills
48 dressed · 5 inactive · 1 never used
75Daryl WilliamsT · Every snap100%57 snaps
79Spencer BrownT · Every snap100%57 snaps
73Dion DawkinsT · Every snap100%57 snaps
17Josh AllenQB · Every snap100%57 snaps
60Mitch MorseC · Every snap100%57 snaps
76Jon FelicianoG · Every snap100%57 snaps
88Dawson KnoxTE · Full-time96%55 snaps
1Emmanuel SandersWR · Heavy rotation79%45 snaps
14Stefon DiggsWR · Heavy rotation74%42 snaps
20Zack MossRB · Heavy rotation74%42 snaps
41Reggie GilliamFB · Rotational39%22 snaps
11Cole BeasleyWR · Rotational39%22 snaps
26Devin SingletaryRB · Rotational26%15 snaps
13Gabriel DavisWR · Rotational25%14 snaps
89Tommy SweeneyTE · Situational18%10 snaps
19Isaiah McKenzieWR · Situational14%8 snaps
15Jake KumerowWR · Situational12%7 snaps
23Micah HydeFS · Situational5%3 snaps
Inactive · 5
Vernon ButlerDTHarrison PhillipsDTMatt MilanoOLBMatt BreidaRBTommy DoyleT
3 players played under 8 snaps, so their shares read as a dash rather than a number. 2 lines have no expected-points read and sit off the plane.
Expected points are modelled in full PPR, so the “vs expected” column stays in that unit whichever format the pills are set to. Switching the pills changes the points column, not the plane.
The field map
Every snap, where it happened
The whole game as one hundred yards. The Chiefs attack right, the Bills attack left, so a change of possession is a reversal you can see. Reading down is the order the snaps were played — not the clock, so a two-minute drill gets the same room as any other fourteen snaps. This game is final.
Bills←Chiefs→
Q1Q2Q3Q4
H.Butker kicks−72% win probabilitymoment 4 of 4
7-H.Butker kicks 12 yards from KC 35 to KC 47, impetus ends at 50. 46-Jaq.Johnson (didn't try to advance) to KC 47 for no gain.
Q2 0:02 · Bills · Kickoff at KC 35 · gained nothing · -0.02 EP · −72.4% win probability
176 snaps placed · 15 without a recorded yard line, left off the map · 4 marked moments — the largest win-probability swings, one per drive.
The Film Room · post-game
Post-game film: 191 plays across 21 drives, personnel groupings on 191 snaps. Everything here paints once the weekly sync ingests the game — there is no live play-level feed in this product, so nothing on this page updates while a game is being played.
Possession by possession
The field rail
9 of 21 drives ended in points. The longest march was BUF moving 85 yards from the BUF 15 for a touchdown. Each bar is the ground a drive actually covered; KC attacks right, BUF attacks left. Hatching marks a trip inside the twenty.
Every snap
Play stream
191 of 191 plays
Team
Quarter
Down
Play type
Expected points added
Event
Charted
Plays shown
191
EPA per play
+0.03
Success rate
46%
Yards
828
Who was on the field
Personnel groupings
Offensive grouping on every pass and run. A group needs five snaps in this game before it gets a number — under that the sample is a coin flip and the cell reads a dash instead. The names of the eleven on the field are only recorded from 2023 onward, so this game gives the grouping without the roster.
Chiefs1 RB, 1 TE, 3 WR61-0.1674%
Bills1 RB, 1 TE, 3 WR25+0.5660%
Bills2 RB, 1 TE, 2 WR19+0.2432%
Chiefs1 RB, 2 TE, 2 WR14-0.2657%
Bills1 RB, 2 TE, 2 WR6+0.0067%
Chiefs2 RB, 2 TE, 1 WR2——
Chiefs1 RB, 3 TE, 1 WR2——
Bills1 RB, 0 TE, 4 WR1——
snapsepapass rate
191 plays · ranked by the win probability each one moved
Every play
Ball
When
Play
Only
Who
191 plays
Bar length is win probability the play moved
1st quarter45 plays
Bills0Chiefs3
Field goal21 plays, from the Chiefs 25 to the Bills 14
Bills6Chiefs3
Bills7Chiefs3
Touchdown10 plays, from the Bills 25 to the Chiefs 9
Fumble lost1 play
Punt6 plays, from the Chiefs 34 to the Chiefs 25
The period ended6 plays, from the Chiefs 20 to the Chiefs 46
2nd quarter55 plays
Bills7Chiefs9
Bills7Chiefs10
Touchdown11 plays, from the Chiefs 41 to the Bills 5
Bills13Chiefs10
Bills14Chiefs10
Touchdown7 plays, from the Bills 25 to the Chiefs 35
Punt5 plays, from the Chiefs 28 to the Chiefs 36
FormationEmpty backfieldOffense on the fieldOne back, one tight end and three receiversDefense on the fieldThree linemen, two linebackers and six backsRoute runGoCoverageCover 2, two deepMan or zoneZoneIn the boxFive defendersRushing the passerThreePressure (charted)The passer was kept cleanTime to throw4.1 seconds
Bills17Chiefs10
Field goal7 plays, from the Bills 26 to the Chiefs 11
Turnover on downs7 plays, from the Chiefs 40 to the Bills 32
Bills23Chiefs10
Bills24Chiefs10
Touchdown3 plays, from the Bills 32 to the Bills 47
Bills24Chiefs13
Field goal13 plays, from the Chiefs 25 to the Bills 34
The period ended2 plays
3rd quarter45 plays
Punt5 plays, from the Bills 25 to the Bills 33
Punt6 plays, from the Chiefs 22 to the Chiefs 41
Punt5 plays, from the Bills 19 to the Chiefs 40
Bills30Chiefs13
Touchdown5 plays, from the Chiefs 8 to the Chiefs 24
Bills31Chiefs13
Intercepted11 plays, from the Chiefs 25 to the Bills 8
Punt4 plays
The period ended6 plays, from the Chiefs 48 to the Bills 15
4th quarter46 plays
Bills31Chiefs19
Bills31Chiefs20
Touchdown4 plays, from the Bills 10 to the Bills 1
Bills37Chiefs20
Bills38Chiefs20
Touchdown17 plays, from the Bills 15 to the Chiefs 8
Fumble lost13 plays, from the Chiefs 23 to the Bills 15
The period ended12 plays, from the Bills 35 to the Chiefs 42
Win probability is the league play-by-play model, 98.5% of plays · a dash means none was published
The cards are drawn from the play-by-play sync, not live, and each one says so on its face.
Closing number vs result
Betting context
Closing spread
Chiefs -2.5
Closing total
57
Bills moneyline
+121
Chiefs moneyline
-134
Chiefs closed -2.5 and lost outright — an upset against the closing number.
Total closed 57; the game landed 58 — over by 1.0.
Conditions and crew
Game environment
Venue
GEHA Field at Arrowhead Stadium
Roof / surface
outdoors · grass
Kickoff weather
Mild, 68°F at kickoff; a light breeze at 7 mph out of the north; 0.22 in of precipitation; moderate rain.
Referee
Carl Cheffers
Rest
Bills 7 days · Chiefs 7 days
Coaches
Sean McDermott vs Andy Reid
1st · 3:21BUF +8% win prob(3:21) (Shotgun) 17-J.Allen pass incomplete short right [51-M.Danna]. PENALTY on BUF-17-J.Allen, Intentional Grounding, 18 yards, enforced at KC 35. Penalty on BUF-1-E.Sanders, Illegal Motion, declined.
2nd · 14:23KC +6% win prob(14:23) (Shotgun) 15-P.Mahomes pass incomplete short right to 31-Da.Williams [96-C.Basham]. PENALTY on BUF-33-S.Neal, Defensive Holding, 5 yards, enforced at 50 - No Play.
