Red Sox vs. Mariners Odds & Betting Predictions - June 21, 2026

Red Sox at Mariners

8:10 pm • NESN

Boston Red Sox

Seattle Mariners

pitcher		team	era	w-l
L.Gilbert			3.43	5-4
P.Tolle			2.93	3-4

MatchupOpenSpreadTotalMoneyline
Red Sox 31-43	+1.5	+1.5-191	o6.5-115	+119
Mariners 39-39	u7	-1.5+155	u6.5-105	-143

Sunday 8:10 p.m.

June 21, 2026

T-Mobile ParkSeattle

71°Fahrenheit

0%Rain

5Wind

Under 3.5 (F5)-125

1.25u

Under 6.5-105

1.05u

R.Refsnyder u0.5 Hits+113

THE BAT X is forecasting 0.56 hits for Rob Refsnyder compared to 0.73 hits implied by the oddsmakers, so I believe there is value here. If you take the under, you'd be projected to win 57% of the time, resulting in a 21% ROI. Based on a $100 wager, the expected value here would be $21.28. This play is good down to at least -107. Love THE BAT X? Get all of Carty's sports betting projections at EV Analytics https://evanalytics.com/subscribe/mlb?ref=zdlkmgz

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Jun 21, 2026 UTC
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No props found

MLB Public Betting

Mariners are 2-3 in their last 5 games.
Mariners are 2-3 in their last 5 games against the spread
Mariners are 15-23 in their road games against the spread
The totals have gone OVER in 2 of Mariners' last 5 games
The totals have gone OVER in 19 of Mariners' 40 last games at home

Against the Spread (ATS) History

	overall	home	away	favorite	underdog
Mariners	29-49	14-26	15-23	27-45	2-4
Red Sox	30-44	12-25	18-19	17-29	12-15

Over/Under History

	overall	home o/u	away o/u	favorite o/u	underdog o/u
Mariners	37-38-3	19-20-1	18-18-2	35-34-3	2-4
Red Sox	33-38-3	13-22-2	20-16-1	20-24-2	13-13-1

Straight-Up (ML) History

	overall	home	away	favorite	underdog
Mariners	39-39	21-19	18-20	37-35	2-4
Red Sox	31-43	12-25	19-18	19-27	11-16

date	opponent	score	spread	over/under	moneyline
Jun 21st	BOS	L 1-5	-1.5 L	U 7	BOS -128
Jun 20th	BOS	L 2-6	+1.5 L	O 6.5	BOS -116
Jun 18th	BAL	W 3-0	-1.5 W	U 7.5	SEA -129
Jun 18th	BAL	L 3-5	-1.5 L	O 7.5	BAL -135
Jun 17th	BAL	W 3-1	-1.5 W	U 7.5	SEA -150

Tanner Houck
SP
Houck is out with arm
Out
Triston Casas
1B
Casas is out with knee
Out
Patrick Sandoval
SP
Sandoval is out with elbow
Out
Kutter Crawford
SP
Crawford is out with wrist
Out
Romy Gonzalez
1B
Gonzalez is out with shoulder
Out

See more MLB Injuries

PITCHER		W-L	ERA	WHIP	K/9
LP.Tolle, P		3-4	2.93	1.063	9.26

HITTERS	AVG	OBP	SLG	HR
1M.Gasper, C	.258	.311	.330	0
2C.Rafaela, CF	.286	.338	.451	7
3W.Abreu, RF	.275	.334	.433	9
4W.Contreras, 1B	.286	.383	.533	16
5J.Duran, LF	.207	.266	.382	12
6M.Yoshida, DH	.248	.329	.331	1
7C.Durbin, 3B	.208	.264	.352	5
8M.Mayer, SS	.223	.288	.311	3
9A.Seigler, 2B	.286	.375	.429	0

PITCHER		W-L	ERA	WHIP	K/9
RL.Gilbert, P		5-4	3.43	1.027	9.55

HITTERS	AVG	OBP	SLG	HR
1J.Crawford, 3B	.217	.348	.386	10
2C.Raleigh, DH	.166	.264	.309	7
3J.Rodriguez, CF	.247	.309	.432	14
4J.Naylor, 1B	.253	.313	.370	8
5R.Refsnyder, RF	.133	.207	.224	3
6C.Young, 2B	.252	.316	.362	6
7M.Garver, C	.189	.313	.305	3
8C.Joe, LF	.179	.289	.308	1
9C.Emerson, SS	.220	.290	.495	6