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A’s vs Mariners Prediction, Odds, Start Time: Tuesday’s Expert MLB Pick

A’s vs Mariners Prediction, Odds, Start Time: Tuesday’s Expert MLB Pick article feature image
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Apr 18, 2026; West Sacramento, California, USA; Athletics first baseman Nick Kurtz (16) hits a two run home run during the seventh inning against the Chicago White Sox at Sutter Health Park. Mandatory Credit: Scott Marshall-Imagn Images

The Seattle Mariners host the A's on Tuesday, April 21. First pitch from T-Mobile Park is scheduled for 9:40 p.m. ET. The game will be broadcast on SEAM and MLB.TV.

The Mariners are favored by -166 on the moneyline and by -1.5 on the run line. The Athletics are +140 on the moneyline and +1.5 on the run line. The total is set at 7.5 runs.

Find my MLB picks and A's vs Mariners prediction below, as well as probable pitchers, weather report, and more.


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A's vs Mariners Prediction

  • A's vs Mariners Pick: A's ML (+120 or Better)

My Mariners vs A's best bet is on the A's to win outright. Make sure to find the best odds by checking our live MLB odds page.


A's vs Mariners Odds

A's Logo
Tuesday, April 21
9:40 p.m. ET
MLB.TV
Mariners Logo
A's Odds
Run LineTotalMoneyline
+1.5
-150
8
-105o / -115u
+143
Mariners Odds
Run LineTotalMoneyline
-1.5
+124
8
-105o / -115u
-173
Odds via DraftKings. Get up-to-the-minute MLB odds here.
DraftKings Logo
  • A's vs Mariners Moneyline: A's +140, Mariners -166
  • A's vs Mariners Over/Under: 8
  • A's vs Mariners Run Line: A's -1.5 (+124), Athletics +1.5 (-150)


A's vs Mariners Kalshi Odds


A's vs Mariners Pitchers

Jacob Lopez (LHP, ATH)StatLuis Castillo (RHP, SEA)
1-1W-L0-1
-0.1fWAR (FanGraphs)0.4
6.38 / 3.99ERA / xERA5.40 / 5.60
6.30 / 6.34FIP / xFIP3.30 / 4.23
1.96WHIP1.80
-1.1%K-BB%11.4%
33.3%GB%40.3%
87Stuff+103
99Location+112

A's vs Mariners Preview

I bet on the Athletics on Monday. It’s back to the well for Tuesday!

I don’t believe Seattle has a big offensive edge over Sacramento. At the same time, my numbers give the Athletics a significant edge in defense and base running.

While Luis Castillo is underperforming (.400 BABIP, 58% strand rate), he always underperforms early in the season. He takes a long time to ramp up, and I believe he simply doesn't perform well in cold weather — unfortunately for him, it’s going to be around 50 degrees during this game.

Regardless, Castillo doesn’t look right. His batted-ball numbers are a mess. Last time out against the Padres, he managed just one whiff on 32 combined sliders and changeups thrown.

Seattle has posted a 116 wRC+ against right-handed pitching this season. The Mariners have posted a 62 wRC+ against left-handed pitching this season. Maybe that gives Jacob Lopez a shot at a decent start.


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A's vs Mariners MLB Pick, Best Bet

I don’t know if the A’s can survive a Lopez start against the Mariners. I also don’t know if the A’s can survive another night with this massive bullpen mismatch.

Regardless, I think this number should be closer to +110 or +115. I am mostly banking on Castillo struggling.

Check out today's full episode of Payoff Pitch:

Pick: A's ML (+120 or Better)

Playbook

A's vs Mariners Tuesday Weather Forecast


Get the latest coverage on MLB Weather.
Author Profile
About the Author

Tanner McGrath covers college basketball, college football and Major League Baseball at Action Network. He is a contributor to Payoff Pitch, Action Network’s Major League Baseball betting podcast. He's been working in the space for more than five years with past journalism experience in Canadian collegiate sports, finance and economics. He has an obsession with America East basketball, betting the Miami Marlins and sweating out home underdogs.

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