bayesRatings

Giants at Red Sox

MLB · Friday, Aug 21 · 6:10 PM CT · Fenway Park · Final SF 4 – BOS 6
← MLB / Aug 21

Final Box Score

from the game summary
Team123456789THE
SF001300000470
BOS005001006110
Team box
SF·BOS
7
hits
11
2
home runs
1
3
walks
5
12
strikeouts
3
156
pitches thrown
141
0
errors
0
Top hitters
PlayerTeamH-ABRHRRBI
Willson ContrerasBOS1-2113
Drew GilbertSF2-3112
Wilyer AbreuBOS3-4101
Rafael DeversSF1-3111
Jarren DuranBOS2-3000
Ceddanne RafaelaBOS2-5000
Pitchers
PitcherTeamIPHERBBK
Logan Webb (L)SF2.26532
Sonny Gray (W)BOS6.07426
Aroldis Chapman (S)BOS1.00013

For context, not in our forecast.

Game Flow

score margin
BOS +4
SF +4
123456789
largest lead: BOS 4 · SF 1lead changes: 1

For context, not in our forecast.

Final · our forecast was SF 40%, BOS 60% · Updated Aug 21

Expected margin
BOS by 1.3
Expected score
BOS 4.9 – 3.6 SF
Expected total
8.4
GiantsThe matchupRed Sox
+147Our fair odds−147
3.6Expected runs4.9
−0.14Power rating+0.18
4.0Runs / game4.5
4.6Allowed / game3.8
8.4Hits / game8.4
1.09Home runs / game1.03
2.6Walks drawn / game3.2
52−75Season record68−59
3−7Last 104−6

Prediction markets

Kalshi · Polymarket US · ProphetX · Novig
SF chance · BOS chance
Our model fair40.5%59.5%
Kalshi39.6%64.6%
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
SFSan Francisco Giants+14740%+15239.6%———
BOSBoston Red Sox−14760%−18364.6%———
SpreadBOS by 1.3
SFSan Francisco Giants+1.3our margin————
BOSBoston Red Sox−1.3our margin————
Totalwe expect 8.4
Over8.4our total————
Under8.4our 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 1.3 expected
San Francisco Giants by 14 runs: <1%San Francisco Giants by 13 runs: <1%San Francisco Giants by 12 runs: <1%San Francisco Giants by 11 runs: <1%San Francisco Giants by 10 runs: <1%San Francisco Giants by 9 runs: <1%San Francisco Giants by 8 runs: 1%San Francisco Giants by 7 runs: 1%San Francisco Giants by 6 runs: 2%San Francisco Giants by 5 runs: 3%San Francisco Giants by 4 runs: 4%San Francisco Giants by 3 runs: 5%San Francisco Giants by 2 runs: 8%San Francisco Giants by 1 run: 16%Boston Red Sox by 1 run: 12%Boston Red Sox by 2 runs: 11%Boston Red Sox by 3 runs: 9%Boston Red Sox by 4 runs: 7%Boston Red Sox by 5 runs: 6%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%
← SF wins byBOS wins by →
Boston Red Sox wins by 2 or more47%
Boston Red Sox wins by 3 or more36%
San Francisco Giants wins by 2 or more24%
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

8.4 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: 4%13 runs: 5%14 runs: 3%15 runs: 3%16 runs: 2%17 runs: 1%18 runs: 1%19 runs: 1%20 runs: <1%21 runs: <1%22 runs: <1%
Total runs, both teams
Total over 6.564%
Total over 8.544%
Total over 10.528%
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
SFLogan Webb SP · last 3 starts: 20.0 IP, 0.90 ERA, 17 Kstarted
BOSSonny Gray SP · last 3 starts: 19.0 IP, 0.95 ERA, 19 Kstarted

Starting pitchers are part of our forecast.

Rest and Schedule

before this game
SF·BOS
Aug 20 at CLE
last game
Aug 19 vs ARI
0 days
days of rest
1 day
6
games in last 7 days
6
4th straight road game
home / road
4th straight home game

For context, not in our forecast.

Team Comparison

2026 season · box-score averages from 127+ games
SF·BOS
−0.14
rating (0 = average)
+0.18
4.0
runs / game
4.5
4.6
runs allowed / game
3.8
52−75
season record
68−59
29−33
home record
31−32
23−42
away record
37−27
L1
streak
L1
3−7
last 10
4−6
8.4
hits / game
8.4
1.09
home runs / game
1.03
2.6
walks drawn / game
3.2
7.9
batter strikeouts / game
8.1
7.6
pitcher strikeouts / game
8.5
0.66
errors / game
0.49

Rating Trend

SF · BOS · 146 days
San Francisco GiantsBoston Red Sox
Rating (0 = average team)

Head to Head

last 9 meetings · BOS 4−5
Jun 22, 2025at SFSF 9 − 5
Jun 21, 2025at SFSF 3 − 2
Jun 20, 2025at SFBOS 7 − 5
May 2, 2024at BOSSF 3 − 1
May 1, 2024at BOSBOS 6 − 2
Apr 30, 2024at BOSBOS 4 − 0
Jul 30, 2023at SFSF 4 − 3
Jul 29, 2023at SFSF 3 − 2
Jul 28, 2023at SFBOS 3 − 2

SF · Last 10

3−7 · streak L1
Aug 20at CLE2 − 5L
Aug 19at CLE1 − 0W
Aug 18at CLE1 − 8L
Aug 16vs COL7 − 13L
Aug 15vs COL7 − 1W
Aug 14vs COL2 − 5L
Aug 12vs HOU1 − 2L
Aug 11vs HOU4 − 1W
Aug 10vs HOU3 − 6L
Aug 9vs DET1 − 3L

BOS · Last 10

4−6 · streak L1
Aug 19vs ARI6 − 7L
Aug 18vs ARI9 − 4W
Aug 17vs ARI11 − 1W
Aug 16at PIT3 − 8L
Aug 15at PIT4 − 0W
Aug 14at PIT4 − 8L
Aug 13at TOR7 − 0W
Aug 12at TOR4 − 6L
Aug 11at TOR3 − 5L
Aug 10at TOR1 − 2L