bayesRatings

Giants at Diamondbacks

MLB · Wednesday, May 20 · 2:40 PM CT · Chase Field · Final SF 3 – ARI 6
← MLB / May 20

Final Box Score

from the game summary
Team123456789THE
SF110100000380
ARI10203000690
Team box
SF·ARI
8
hits
9
1
home runs
1
1
walks
1
5
strikeouts
10
118
pitches thrown
122
0
errors
0
Top hitters
PlayerTeamH-ABRHRRBI
Ketel MarteARI3-3312
Geraldo PerdomoARI1-3003
Casey SchmittSF1-4111
Jose FernandezARI2-4000
Ryan WaldschmidtARI2-3200
Matt ChapmanSF2-4200
Pitchers
PitcherTeamIPHERBBK
Tyler Mahle (L)SF5.08606
Merrill Kelly (W)ARI6.08304
Paul Sewald (S)ARI1.00001

For context, not in our forecast.

Game Flow

score margin
ARI +3
SF +3
123456789
largest lead: ARI 3 · SF 1lead changes: 1

For context, not in our forecast.

Final · our forecast was SF 45%, ARI 55% · Updated May 20

Expected margin
Even
Expected score
ARI 5.0 – 4.5 SF
Expected total
9.5
GiantsThe matchupDiamondbacks
+120Our fair odds−120
4.5Expected runs5.0
−0.07Power rating+0.03
3.5Runs / game4.6
4.5Allowed / game4.7
8.3Hits / game8.2
0.82Home runs / game0.91
2.1Walks drawn / game3.1
20−29Season record24−23
5−5Last 107−3

Prediction markets

Kalshi · Polymarket US · ProphetX · Novig
SF chance · ARI chance
Our model fair45.5%54.5%
Kalshi51.7%52.7%
Polymarket USno two-sided price
ProphetXno two-sided price
Novigno two-sided price
Full price table
TeamOur modelfairKalshipre-game · 2:40 PM CTPolymarket US ProphetX Novig 
Moneyline
SFSan Francisco Giants+12045%−10751.8%———
ARIArizona Diamondbacks−12055%−11252.7%———
Spreadabout even
SFSan Francisco Giants+0.4our margin————
ARIArizona Diamondbacks−0.4our margin————
Totalwe expect 9.5
Over9.5our total————
Under9.5our 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

Even game 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: 2%San Francisco Giants by 6 runs: 3%San Francisco Giants by 5 runs: 4%San Francisco Giants by 4 runs: 5%San Francisco Giants by 3 runs: 7%San Francisco Giants by 2 runs: 9%San Francisco Giants by 1 run: 12%Arizona Diamondbacks by 1 run: 15%Arizona Diamondbacks by 2 runs: 10%Arizona Diamondbacks by 3 runs: 7%Arizona Diamondbacks by 4 runs: 6%Arizona Diamondbacks by 5 runs: 5%Arizona Diamondbacks by 6 runs: 3%Arizona Diamondbacks by 7 runs: 3%Arizona Diamondbacks by 8 runs: 2%Arizona Diamondbacks by 9 runs: 1%Arizona Diamondbacks by 10 runs: 1%Arizona Diamondbacks by 11 runs: 1%Arizona Diamondbacks by 12 runs: <1%Arizona Diamondbacks by 13 runs: <1%Arizona Diamondbacks by 14 runs: <1%
← SF wins byARI wins by →
Arizona Diamondbacks wins by 2 or more40%
Arizona Diamondbacks wins by 3 or more30%
San Francisco Giants wins by 2 or more34%
Decided by one run27%

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

9.5 expected
1 runs: 1%2 runs: 1%3 runs: 5%4 runs: 4%5 runs: 9%6 runs: 7%7 runs: 11%8 runs: 7%9 runs: 10%10 runs: 7%11 runs: 8%12 runs: 5%13 runs: 6%14 runs: 4%15 runs: 4%16 runs: 2%17 runs: 2%18 runs: 1%19 runs: 1%20 runs: 1%21 runs: 1%22 runs: <1%23 runs: <1%24 runs: <1%25 runs: <1%
Total runs, both teams
Total over 7.562%
Total over 9.544%
Total over 11.529%
Total from 8 to 1133%

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
SFTyler Mahle SP · last 3 starts: 16.0 IP, 5.06 ERA, 19 Kstarted
ARIMerrill Kelly SP · last 3 starts: 20.1 IP, 3.54 ERA, 14 Kstarted

Starting pitchers are part of our forecast.

Rest and Schedule

before this game
SF·ARI
May 19 at ARI
last game
May 19 vs SF
0 days
days of rest
0 days
7
games in last 7 days
6
10th straight road game
home / road
3rd straight home game

For context, not in our forecast.

Team Comparison

2026 season · box-score averages from 47+ games
SF·ARI
−0.07
rating (0 = average)
+0.03
3.5
runs / game
4.6
4.5
runs allowed / game
4.7
20−29
season record
24−23
10−12
home record
14−9
10−17
away record
10−14
L2
streak
W3
5−5
last 10
7−3
8.3
hits / game
8.2
0.82
home runs / game
0.91
2.1
walks drawn / game
3.1
7.9
batter strikeouts / game
7.6
7.8
pitcher strikeouts / game
7.4
0.59
errors / game
0.47

Rating Trend

SF · ARI · 56 days
San Francisco GiantsArizona Diamondbacks
Rating (0 = average team)

Head to Head

last 10 meetings · ARI 5−5
May 19at ARIARI 5 − 3
May 18at ARIARI 12 − 2
Sep 17, 2025at ARISF 5 − 1
Sep 16, 2025at ARIARI 6 − 5
Sep 15, 2025at ARIARI 8 − 1
Sep 10, 2025at SFARI 5 − 3
Sep 9, 2025at SFSF 5 − 3
Sep 8, 2025at SFSF 11 − 5
Jul 3, 2025at ARISF 7 − 2
Jul 2, 2025at ARISF 6 − 5

SF · Last 10

5−5 · streak L2
May 19at ARI3 − 5L
May 18at ARI2 − 12L
May 17at ATH10 − 1W
May 16at ATH6 − 4W
May 15at ATH2 − 5L
May 14at LAD2 − 5L
May 13at LAD0 − 4L
May 12at LAD6 − 2W
May 11at LAD9 − 3W
May 10vs PIT7 − 6W

ARI · Last 10

7−3 · streak W3
May 19vs SF5 − 3W
May 18vs SF12 − 2W
May 17at COL8 − 6W
May 16at COL2 − 4L
May 15at COL9 − 1W
May 13at TEX5 − 6L
May 12at TEX4 − 7L
May 11at TEX1 − 0W
May 10vs NYM5 − 1W
May 9vs NYM2 − 1W