bayesRatings

Royals at Red Sox

MLB · Friday, Sep 11 · 6:10 PM CT · Fenway Park · Final KC 3 – BOS 2
← MLB / Sep 11

Final Box Score

from the game summary
Team123456789THE
KC1020000003100
BOS000020000280
Team box
KC·BOS
10
hits
8
0
home runs
1
5
walks
2
8
strikeouts
10
146
pitches thrown
143
0
errors
0
Top hitters
PlayerTeamH-ABRHRRBI
Mickey GasperBOS1-3111
Wilyer AbreuBOS2-4001
Salvador PerezKC2-4001
Carter JensenKC2-5201
Vinnie PasquantinoKC1-5001
Michael MasseyKC2-4000
Pitchers
PitcherTeamIPHERBBK
Seth Lugo (W)KC5.07227
Steven Cruz (S)KC1.00001
Sonny Gray (L)BOS6.06325

For context, not in our forecast.

Game Flow

score margin
BOS +3
KC +3
123456789
largest lead: BOS 0 · KC 3lead changes: 0

For context, not in our forecast.

Final · our forecast was KC 41%, BOS 59% · Updated Sep 11

Expected margin
BOS by 1.1
Expected score
BOS 4.8 – 3.7 KC
Expected total
8.5
RoyalsThe matchupRed Sox
+144Our fair odds−144
3.7Expected runs4.8
−0.12Power rating+0.17
4.3Runs / game4.4
4.9Allowed / game3.9
8.3Hits / game8.3
1.05Home runs / game1.04
3.2Walks drawn / game3.2
65−82Season record80−67
3−7Last 106−4

Prediction markets

Kalshi · Polymarket US · ProphetX · Novig
KC chance · BOS chance
Our model fair40.9%59.1%
Kalshi36.6%67.6%
Polymarket USno two-sided price
ProphetXno two-sided price
Novigno two-sided price
Full price table
TeamOur modelfairKalshipre-game · 6:10 PM CTPolymarket US ProphetX Novig 
Moneyline
KCKansas City Royals+14441%+17336.6%———
BOSBoston Red Sox−14459%−20867.6%———
SpreadBOS by 1.1
KCKansas City Royals+1.1our margin————
BOSBoston Red Sox−1.1our margin————
Totalwe expect 8.5
Over8.5our total————
Under8.5our total————

These are each venue’s last prices before the start (Kalshi’s moneyline: its pre-game close). Odds are the price to buy that side now, taker fee included; the small percent is the implied chance of that same price. Highlighted is the best price in the row among venues on the same line. — means not listed (hover or tap for why). A market price is not the true chance of winning.

Margin range

Boston Red Sox by 1.1 expected
Kansas City Royals by 14 runs: <1%Kansas City Royals by 13 runs: <1%Kansas City Royals by 12 runs: <1%Kansas City Royals by 11 runs: <1%Kansas City Royals by 10 runs: <1%Kansas City Royals by 9 runs: <1%Kansas City Royals by 8 runs: 1%Kansas City Royals by 7 runs: 1%Kansas City Royals by 6 runs: 2%Kansas City Royals by 5 runs: 3%Kansas City Royals by 4 runs: 4%Kansas City Royals by 3 runs: 6%Kansas City Royals by 2 runs: 9%Kansas City Royals by 1 run: 14%Boston Red Sox by 1 run: 14%Boston Red Sox by 2 runs: 11%Boston Red Sox by 3 runs: 8%Boston Red Sox by 4 runs: 7%Boston Red Sox by 5 runs: 5%Boston Red Sox by 6 runs: 4%Boston Red Sox by 7 runs: 3%Boston Red Sox by 8 runs: 2%Boston Red Sox by 9 runs: 2%Boston Red Sox by 10 runs: 1%Boston Red Sox by 11 runs: 1%Boston Red Sox by 12 runs: <1%Boston Red Sox by 13 runs: <1%Boston Red Sox by 14 runs: <1%
← KC wins byBOS wins by →
Boston Red Sox wins by 2 or more45%
Boston Red Sox wins by 3 or more34%
Kansas City Royals wins by 2 or more26%
Decided by one run28%

Centered on the expected margin above; shape from each team's expected runs, with ties after nine settled as one-run games, matched to 14,698 past MLB games.

Total range

8.5 expected
1 runs: 2%2 runs: 2%3 runs: 7%4 runs: 5%5 runs: 11%6 runs: 8%7 runs: 12%8 runs: 8%9 runs: 10%10 runs: 6%11 runs: 7%12 runs: 5%13 runs: 5%14 runs: 3%15 runs: 3%16 runs: 2%17 runs: 2%18 runs: 1%19 runs: 1%20 runs: <1%21 runs: <1%22 runs: <1%23 runs: <1%
Total runs, both teams
Total over 6.565%
Total over 8.545%
Total over 10.529%
Total from 7 to 1037%

Centered on the expected total above; shape from each team's expected runs, with ties after nine settled as one-run games, matched to 14,698 past MLB games.

Starting Pitchers

from the box score
KCSeth Lugo SP · last 3 starts: 13.2 IP, 8.56 ERA, 8 Kstarted
BOSSonny Gray SP · last 3 starts: 18.0 IP, 3.00 ERA, 18 Kstarted

Starting pitchers are part of our forecast.

Rest and Schedule

before this game
KC·BOS
Sep 9 vs ARI
last game
Sep 9 vs LAA
1 day
days of rest
1 day
6
games in last 7 days
6
road after a home game
home / road
4th straight home game

For context, not in our forecast.

Team Comparison

2026 season · box-score averages from 147+ games
KC·BOS
−0.12
rating (0 = average)
+0.17
4.3
runs / game
4.4
4.9
runs allowed / game
3.9
65−82
season record
80−67
39−36
home record
36−36
26−46
away record
44−31
W1
streak
L2
3−7
last 10
6−4
8.3
hits / game
8.3
1.05
home runs / game
1.04
3.2
walks drawn / game
3.2
7.8
batter strikeouts / game
8.1
7.2
pitcher strikeouts / game
8.6
0.44
errors / game
0.51

Rating Trend

KC · BOS · 167 days
Kansas City RoyalsBoston Red Sox
Rating (0 = average team)

Head to Head

last 10 meetings · BOS 7−3
May 20at KCBOS 4 − 3
May 19at KCBOS 7 − 1
May 18at KCBOS 3 − 1
Aug 6, 2025at BOSKC 7 − 3
Aug 5, 2025at BOSBOS 6 − 2
Aug 4, 2025at BOSBOS 8 − 5
May 11, 2025at KCBOS 3 − 1
May 10, 2025at KCBOS 10 − 1
May 9, 2025at KCKC 2 − 1
Aug 7, 2024at KCKC 8 − 4

KC · Last 10

3−7 · streak W1
Sep 9vs ARI5 − 2W
Sep 8vs ARI3 − 5L
Sep 7vs ARI4 − 5L
Sep 6vs TOR6 − 1W
Sep 5vs TOR3 − 4L
Sep 4vs TOR2 − 9L
Sep 3vs MIA7 − 3W
Sep 2vs MIA6 − 9L
Sep 1vs MIA3 − 6L
Aug 30at CLE1 − 11L

BOS · Last 10

6−4 · streak L2
Sep 9vs LAA4 − 6L
Sep 8vs LAA1 − 6L
Sep 7vs LAA5 − 2W
Sep 6at BAL3 − 1W
Sep 5at BAL5 − 0W
Sep 4at BAL1 − 0W
Sep 3at BAL6 − 5W
Sep 2vs SEA3 − 8L
Sep 1vs SEA6 − 9L
Aug 31vs SEA9 − 8W