SF vs BOS prediction for August 21, 2026: Our Monte Carlo simulation ran 10,000 game iterations and projects BOS 5.6 - SF 5.5. BOS is favored with a 53.9% win probability. The run line is -1.5 and the total is 7.5. Model projects 11.2 total runs.
BOS
5.6
Projected Score
VS
O/U 7.5
SF
5.5
Projected Score
Win Probability
BOSSF
-1.5
Run Line (BOS)
7.5
Total Line
10,000
Simulations
Calibrated accuracy at this confidence: 58.1% (3,320 games)
Projected Runs Range 10th – 90th percentile
SF
467
BOS
468
Projected
BOS 5.6 — SF 5.5
Actual
BOS 6 — SF 4
Starting Pitcher Matchup
Logan Webb R
SF
usagewhiffbar labels show usage · mph
SI29%92 mph9% whiff
CH25%86 mph27% whiff
ST19%84 mph20% whiff
Sonny Gray R
BOS
usagewhiffbar labels show usage · mph
SI22%92 mph13% whiff
ST20%85 mph38% whiff
FC19%88 mph14% whiff
Weather Impact
Fenway Park
68°F6 mph wind
HR: 0.986 Total: 0.991
5mph in
Bullpen Comparison
SF
4.76ERA
4.60FIP
7.39K/9
4.60BB/9
1.48WHIP
BOS
3.29ERA
3.50FIP
9.52K/9
3.08BB/9
1.22WHIP
Betting Edges
First 5 Innings & NRFI
SF F5
3.0 runs
44.4% win
BOS F5
3.0 runs
42.5% win
F5 Total
6.0
NRFI
48.8%
YRFI
51.2%
Avg 1st Inn Runs
1.21
HR Spotlight
Injury Report
SF8 injured
Keaton Winn RP15-DAY-IL
Marcelo Mayer 2B10-DAY-IL
Daniel Susac C60-DAY-IL
Harrison Bader CF60-DAY-IL
Jesus Rodriguez C10-DAY-IL
Matt Chapman 3B60-DAY-IL
+2 more
BOS8 injured
Roman Anthony LF60-DAY-IL
Masataka Yoshida DH10-DAY-IL
Tanner Houck SP60-DAY-IL
Trevor Story SS60-DAY-IL
Justin Slaten RP15-DAY-IL
Isiah Kiner-Falefa 2B60-DAY-IL
+2 more
AI Intelligence Analysis
Edge Analysis
How this prediction was generated: This page shows output from the Olympus Bets MLB Baseball Monte Carlo engine. Each game is simulated 10,000 times using real-time team data, injury reports, and current odds. Probabilities are calibrated using Bayesian methods and sized via the Kelly Criterion. Probabilities are calibrated using Bayesian methods and sized via the Kelly Criterion. Full methodology →
Permanent record: this game page is retired 90 days after the event. The full graded MLB 2026 record — every pick, win rate, units and ROI — lives on the MLB 2026 season report card.