Mariners vs A's Picks and Predictions: Wild Card Hopefuls Try to Stay In Postseason Race

Both Oakland and Seattle are still in the wild card race heading into a massive four-game set at RingCentral Coliseum. The A's are MLB betting favorites at home, but check out why we're leaning towards the visiting M's tonight.

Last Updated: Sep 20, 2021 10:40 AM ET Read Time: 4 min
Jarred Kelenic Seattle Mariners MLB
Photo By - USA TODAY Sports

The final game on the MLB betting board for Monday is a West Coast showdown between the Seattle Mariners and Oakland A's.

This will be the first contest in a four-game set at RingCentral Coliseum in Oakland and will be a crucial series for the AL playoff picture: The A's are just two games outside of the final AL Wild Card spot and are -156 home favorites for tonight.  

Here are our best free Mariners vs. Athletics picks and predictions for Monday, September 20, with the first pitch scheduled for 9:40 p.m. ET.

Mariners vs A's game info

Location: RingCentral Coliseum, Oakland, CA
Date: Monday, September 20, 2021
Time: 9:40 p.m. ET

Mariners vs A's odds

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Mariners vs A's betting preview

Starting pitchers

Tyler Anderson (6-9, 4.14 ERA): The Mariners traded for Anderson in July and he's been solid with his new club, pitching to a 3.67 ERA with a 1.22 WHIP in nine starts with Seattle. The southpaw looked decent in his last outing, allowing one run on four hits before getting taken out midway through the fifth inning against the Red Sox. 

Sean Manaea (10-9, 3.95 ERA): The left-hander has had mixed results this season, pitching to a 1.23 WHIP with an OBA of .255 across 29 starts. He's coming off a rough outing against the Royals, where he surrendered nine hits and five earned runs in five innings. That said, he's been outstanding in a pair of starts against the Mariners this year, allowing just seven hits and one run through 16 innings. 


Be sure to monitor the gametime conditions with our MLB weather info.

Key injuries

Mariners: Kyle Seager 3B (Questionable). 
A's: Mitch Moreland 1B (Out), Ramon Laureano OF (Out).
Find our latest MLB injury reports.

Betting trend to know

The Mariners are 5-0 in the last five games in the head-to-head with Oakland, with the Under cashing in six of the last seven contests between these AL West foes. Find more MLB betting trends for Mariners vs. A's.

Moneyline pick

The Oakland A's have won five games in a row and, with an 82-67 record, are just two games outside of the final wild-card spot in the AL. The Mariners are fresh off a series in Kansas City where they took two of three games and they're still very much in postseason contention themselves, sitting just two games behind the A's.

Neither team has been particularly productive at the dish lately, with the A's 20th in the majors in OPS (.721) over the last 15 days, while the M's are just one spot below them with an OPS of .710.

The A's will send Sean Manaea to the mound today and he has already pitched a pair of gems against Seattle this year, including a complete-game shutout on June 2. That said, the last time he played against them was on July 22 — and his season has really gone downhill since then, as Manaea has a 6.92 ERA with a 1.51 WHIP in eight starts since the beginning of August.

The Mariners will respond with midseason acquisition Tyler Anderson, who has a 3.50 ERA with a 1.24 WHIP in eight starts over the same time span. 

Seattle has been undervalued on the road all season but has gone 38-36 — for a profit of plus-15.02 units. It has also gone 9-3 in its last 12 away contests and is 4-1 in its last five trips to Oakland. Take the M's at +150.  

PREDICTION: Seattle (+150)

Over/Under pick

Neither team has a stud starter on the mound tonight but it might not make a difference, given the tense postseason atmosphere we could see between a pair of division rivals.

The A's home field isn't quite as friendly towards pitchers as T-Mobile Park but it has an expansive foul ball territory, which leads to more outs than the typical ballpark. Oakland has an OPS of .699 at home while plating 4.18 runs per game, with both numbers significantly lower than its batting numbers on the road.

As a matter of fact, the A's have plated just 3.77 runs per game over their last 13 home games. With the Under going 6-1-1 in the last eight meetings between these teams at RingCentral Coliseum, back it again tonight. 

PREDICTION: Under 8 (-110)

Mariners vs A's betting card

  • Seattle ML (+150)
  • Under 8 (-110)

Picks made on 9/20/2021 at 10 a.m. ET

MLB parlays

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