San Francisco Giants vs Boston Red Sox: MLB Prediction, Pick & Odds — Aug 21, 2026

52-74

PregameFri, 7:10 PM EDTMLB.TV

BOS

68-59

Verdict

Pass · no edge tonight.

The model doesn't see daylight against the posted line on this game. We don't surface negative-EV picks; check the drill-down for sub-model context.

Why this matchup

2 signals · model + market

Park factor

104 total idx

Fenway Park run environment

Park factor boosts run scoring, so contact quality matters more tonight here.

Recent form

4-6

BOS +1.1 vs SF -2.0 margin

BOS brings the hotter last-ten margin into this matchup tonight with balance.

Fenway Park · Boston, Massachusetts

Drill down

Sub-model tables · ensemble breakdown · last meeting · book shop · player props

Pregame · scouting report

The matchup, end-to-end.

Probable starters, projected lineups, head-to-head this season, our model edge against the market — every angle on one surface.

Away starter

Logan Webb

SP · #62

8-7

W-L

3.50

ERA

1.06

WHIP

110

139.0

Last 3 starts

vsCOLW(8-7)6.0 IP1 ER7 K

vsDET-8.0 IP1 ER2 K

@TEXW(7-7)6.0 IP0 ER8 K

Home starter

Sonny Gray

SP · #54

15-3

W-L

2.65

ERA

1.15

WHIP

117

132.2

Last 3 starts

@PITW(15-3)7.0 IP0 ER7 K

@TORL(14-3)6.0 IP2 ER4 K

vsCHWW(14-2)6.0 IP0 ER8 K

Vegas line

Lines post once a sportsbook releases them.

Model edge

Win prob35% / 65%

LeanHome · 15pp

Confidence★ Lock

Head to head

SeriesSeries starts 8/21

TypeRegular Season Series

Scouting report · pre-game

BOS vs SF.

BOS is 4-6 recently; SF is 3-7.

65.1%

model · BOS win prob

Recent form

BOS4–6+1.1
SF3–7-2.0

Situational

BOS2d rest
SF2d rest
+0.0d differential

Rest is even. BOS has 0 straight road games; SF has 2.

Model angle

Weather and park add about 0.3 runs from the total environment.

▲Weather + park+0.3pp

Players to watch

Payton TolleBOS
6.6strikeouts · ±3.2
Payton Tolle · 6.6 K · last-10 6.8 vs season 6.4.
Sonny GrayBOS
5.8strikeouts · ±2.7
Sonny Gray · 5.8 K · last-10 6.2 vs season 5.1.
Ranger SuarezBOS
5.1strikeouts · ±2.5
Ranger Suarez · 5.1 K · last-10 5 vs season 5.1.

Aggregated from r107 anatomy · r109 CLV history · r112 calibration · r118 line moves · r124 player projections · refreshes every 5 minutes

Model ensemble · how the prediction is built

3 sub-models, blended.

Each sub-model uses a different rating substrate. Bayesian model averaging weights them by rolling Brier score so the ensemble inherits each model's strengths. Disagreement flags games where the sub-models don't see eye-to-eye — lower confidence, wider band.

65.5%

ensemble · BOS favored

Elo Static
68.7%
P(BOS win)
33%
weight
Elo Pitching
69.7%
P(BOS win)
33%
weight
Bullpen Park
69.7%
P(BOS win)
34%
weight

Disagreement

0.47 pp

weighted σ across sub-models

Confidence

97% · high

maps from disagreement

Substrate count

3 / 3 active

ones with full inputs tonight

Weights recalibrated nightly on a 90-day rolling window with strict point-in-time correctness — no model gets credit for a game it hasn't seen. Headline % is Platt-scaled per league; sub-model rows show raw BMA inputs.

Player projections

BOS vs SF.

Per-player stat projections built from a recency-weighted blend of the last ten games, season average, and matchup context. Confidence reflects sample size and stability — the top of each list is who to watch.

126

projections · 96 high confidence

Strikeouts

Payton TolleBOS
6.6± 3.2high
Sonny GrayBOS
5.8± 2.7high
Ranger SuarezBOS
5.1± 2.5high

Hits

Ceddanne RafaelaBOS
1.2± 0.9high
Caleb DurbinBOS
1.0± 1.2high
Nick SogardBOS
0.9± 0.9high

Total bases

Ceddanne RafaelaBOS
1.9± 1.9high
Wilyer AbreuBOS
1.9± 2.5high
Willson ContrerasBOS
1.8± 2.1high

RBIs

Caleb DurbinBOS
0.7± 1.6high
Turner HillSF
0.7± 0.8low
Drew GilbertSF
0.6± 1.0high

Earned runs

Carson WhisenhuntSF
3.6± 2.7low
Landen RouppSF
2.7± 1.9high
Patrick SandovalBOS
2.6± 3.1low

Projections recompute every 30 minutes · prop lines plug in once sportsbook ingest lands

Matchup · 2026

Team rate stats vs league

MLB Stats API

league avg

BOS

.712

OPS

.719

▶

.728

.306

OBP

.318

▶

.323

4.06

Runs / G

4.50

▶

4.53

4.35

Team ERA

4.17

▶

3.52

1.35

WHIP

1.30

▶

1.22

7.7

K / 9

8.5

▶

8.6

The One model★ Lock

Fri, Aug 21

Giants

71-85

vs65.1%BOS

BOS★

Red Sox

78-73

SF 34.9%win prob65.1% BOS

BOS 1563 · SF 1450Box score→

Team pages

San Francisco GiantsBoston Red Sox

Elsewhere in the MLB

Data via ESPN · MLB Stats API · Baseball Savant

San Francisco Giants at Boston Red Sox

The matchup, end-to-end.

BOS vs SF.

3 sub-models, blended.

BOS vs SF.

Team rate stats vs league