bayesRatings

Red Sox at Royals

MLB · Monday, May 18 · 6:10 PM CT · Kauffman Stadium · Final BOS 3 – KC 1
← MLB / May 18

Final Box Score

from the game summary
Team123456789THE
BOS000002100390
KC000000100160
Team box
BOS·KC
9
hits
6
1
home runs
0
3
walks
1
8
strikeouts
13
123
pitches thrown
132
0
errors
0
Top hitters
PlayerTeamH-ABRHRRBI
Willson ContrerasBOS1-4112
Jac CaglianoneKC2-4001
Andruw MonasterioBOS2-4000
Mickey GasperBOS2-5100
Connor WongBOS1-4100
Jarren DuranBOS0-2001
Pitchers
PitcherTeamIPHERBBK
Sonny Gray (W)BOS6.05119
Aroldis Chapman (S)BOS1.00001
Seth Lugo (L)KC6.05225

For context, not in our forecast.

Game Flow

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

For context, not in our forecast.

Final · our forecast was BOS 49%, KC 51% · Updated May 18

Expected margin
Even
Expected score
KC 4.0 – 3.9 BOS
Expected total
7.9
Red SoxThe matchupRoyals
+103Our fair odds−103
3.9Expected runs4.0
+0.02Power rating−0.03
3.6Runs / game4.0
4.1Allowed / game4.5
7.8Hits / game7.9
0.72Home runs / game0.98
3.0Walks drawn / game3.6
19−27Season record20−27
4−6Last 103−7

Prediction markets

Kalshi · Polymarket US · ProphetX · Novig
BOS chance · KC chance
Our model fair49.3%50.7%
Kalshi52.7%51.7%
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
BOSBoston Red Sox+10349%−11252.7%———
KCKansas City Royals−10351%−10751.8%———
Spreadabout even
BOSBoston Red Sox+0.1our margin————
KCKansas City Royals−0.1our margin————
Totalwe expect 7.9
Over7.9our total————
Under7.9our 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

Even game expected
Boston Red Sox by 12 runs: <1%Boston Red Sox by 11 runs: <1%Boston Red Sox by 10 runs: <1%Boston Red Sox by 9 runs: 1%Boston Red Sox by 8 runs: 1%Boston Red Sox by 7 runs: 2%Boston Red Sox by 6 runs: 3%Boston Red Sox by 5 runs: 4%Boston Red Sox by 4 runs: 5%Boston Red Sox by 3 runs: 7%Boston Red Sox by 2 runs: 10%Boston Red Sox by 1 run: 16%Kansas City Royals by 1 run: 15%Kansas City Royals by 2 runs: 10%Kansas City Royals by 3 runs: 7%Kansas City Royals by 4 runs: 6%Kansas City Royals by 5 runs: 4%Kansas City Royals by 6 runs: 3%Kansas City Royals by 7 runs: 2%Kansas City Royals by 8 runs: 1%Kansas City Royals by 9 runs: 1%Kansas City Royals by 10 runs: 1%Kansas City Royals by 11 runs: <1%Kansas City Royals by 12 runs: <1%
← BOS wins byKC wins by →
Kansas City Royals wins by 2 or more36%
Kansas City Royals wins by 3 or more25%
Boston Red Sox wins by 2 or more34%
Decided by one run31%

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

7.9 expected
1 runs: 2%2 runs: 2%3 runs: 8%4 runs: 6%5 runs: 13%6 runs: 8%7 runs: 13%8 runs: 8%9 runs: 10%10 runs: 6%11 runs: 7%12 runs: 4%13 runs: 4%14 runs: 2%15 runs: 2%16 runs: 1%17 runs: 1%18 runs: 1%19 runs: 1%20 runs: <1%21 runs: <1%
Total runs, both teams
Total over 5.568%
Total over 7.548%
Total over 9.530%
Total from 6 to 939%

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
BOSSonny Gray SP · last 3 starts: 13.2 IP, 1.32 ERA, 10 Kstarted
KCSeth Lugo SP · last 3 starts: 15.0 IP, 6.60 ERA, 15 Kstarted

Starting pitchers are part of our forecast.

Rest and Schedule

before this game
BOS·KC
May 17 at ATL
last game
May 17 at STL
0 days
days of rest
0 days
6
games in last 7 days
6
4th straight road game
home / road
home after a road game

For context, not in our forecast.

Team Comparison

2026 season · box-score averages from 46+ games
BOS·KC
+0.02
rating (0 = average)
−0.03
3.6
runs / game
4.0
4.1
runs allowed / game
4.5
19−27
season record
20−27
8−14
home record
13−10
11−13
away record
7−17
L1
streak
W1
4−6
last 10
3−7
7.8
hits / game
7.9
0.72
home runs / game
0.98
3.0
walks drawn / game
3.6
8.3
batter strikeouts / game
8.0
8.0
pitcher strikeouts / game
8.3
0.48
errors / game
0.36

Rating Trend

BOS · KC · 54 days
Boston Red SoxKansas City Royals
Rating (0 = average team)

Head to Head

last 10 meetings · KC 3−7
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
Aug 6, 2024at KCBOS 6 − 5
Aug 5, 2024at KCBOS 9 − 5
Jul 14, 2024at BOSBOS 5 − 4

BOS · Last 10

4−6 · streak L1
May 17at ATL1 − 8L
May 16at ATL3 − 2W
May 15at ATL2 − 3L
May 14vs PHI1 − 3L
May 13vs PHI3 − 1W
May 12vs PHI1 − 2L
May 10vs TB1 − 4L
May 8vs TB2 − 0W
May 7vs TB4 − 8L
May 6at DET4 − 0W

KC · Last 10

3−7 · streak W1
May 17at STL2 − 0W
May 16at STL2 − 4L
May 15at STL4 − 5L
May 14at CHW2 − 6L
May 13at CHW5 − 6L
May 12at CHW5 − 6L
May 10vs DET3 − 6L
May 9vs DET5 − 1W
May 8vs DET4 − 3W
May 7vs CLE5 − 8L