Guardians vs Mariners Predictions, Picks, Odds: Pitchers Duel Takes Over the Emerald City

Shane Bieber has had Seattle's number over the years and we like Cleveland's ace to go mano o mano with Luis Castillo on the rubber tonight. Find out more by reading our Guardians vs. Mariners betting picks.

Last Updated: Mar 30, 2023 2:41 PM ET Read Time: 4 min
Shane Bieber Cleveland Guardians MLB
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Opening Day closes with one of the best pitching matchups on the board as Shane Bieber and the Cleveland Guardians face off against Luis Castillo and the Seattle Mariners.

Bieber, a former Cy Young Award winner, is coming off a strong 2022 campaign and was a big part of a surprise Guardians team that won 92 games and finished atop the American League Central last season.

Meanwhile, Luis Castillo was exactly the ace this Mariners staff needed to help them get over the hump and finally qualify for the postseason — something that had been haunting them since 2001.

I break down this pitcher’s duel between two postseason teams from a season ago and bring you my best bet in our free MLB picks and predictions for Guardians vs. Mariners on March 30.

Guardians vs Mariners odds

Guardians vs Mariners predictions

The Cleveland Guardians were one of the biggest surprises of the 2022 season. Thanks to some excellent pitching, timely hitting, and great coaching, the Guardians ended up winning 92 games on the way to the AL Central crown.

Meanwhile, the Seattle Mariners ended a 20-year postseason drought thanks to winning 90 games. The Mariners won their Wild Card series against the Toronto Blue Jays before getting ousted by the eventual World Series champion Houston Astros. With a young core led by superstar-in-the-making Julio Rodriguez, the M's are hoping that was just the beginning.

Both of these teams are looking to build off of their success from last season, and it all starts at the top of their respective rotations.

For Cleveland, that’s Shane Bieber. The 2020 Cy Young Award winner still has solid swing-and-miss stuff and mixes his pitches well. He’ll have a chance to put on a good performance tonight against the Mariners.

One of Seattle’s biggest issues in 2022 was making contact against right-handed pitchers. The Mariners ranked 26th in batting average and 16th in OPS when facing right-handed pitchers last season.

In a lone start against the Mariners last season, Bieber was dominant. He allowed just one earned run on five hits over seven innings while striking out nine. While Seattle made an attempt to address that by trading for Teoscar Hernandez, this lineup could still use more depth.

The Mariners counter Bieber with Luis Castillo. Seattle acquired the right-hander from Cincinnati at the trade deadline last year, and he has been worth every penny. As a member of the M’s, Castillo pitched to a 2.91 FIP and struck out 10.6 batters per nine in 2022. 

He was also fantastic in the postseason, giving up just three runs on 11 hits over 14 2/3 innings against two strong Astros and Blue Jays lineups. 

Considering this Cleveland lineup doesn’t have crazy pop, it's still considered a sub-par lineup and one that Castillo should have the advantage against. This game has pitcher’s duel written all over it and I agree. I’m betting on the Under first five-inning total in this matchup.

Or as it’s known around the Covers’ editorial team, "Bieber Fever".

My best bet: Under 3.5 first five innings (-128 at FanDuel)

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Guardians vs Mariners moneyline analysis

This game opened as pretty much a coin flip with both sides near the -110 mark. As of Thursday afternoon, the Mariners are currently -120 home favorites.

A close line makes sense with Bieber and Castillo on the bump. Additionally, the Guardians and Mariners ranked in the Top 10 when it came to bullpen ERA last season. Each batting order also includes superstars, with Jose Ramirez leading the charge for Cleveland and Rodriguez as the face of Seattle. 

So to me, this will come down to coaching. For my money, Terry Francona is the best manager in baseball. This Cleveland team does all the little things well because of Tito, so the +100 odds would have me leaning ever so slightly toward the Guardians.

Guardians vs Mariners Over/Under analysis

The total for this AL matchup is a low 6.5, which is unsurprising considering the starting pitching and solid bullpens involved. Since I am on the five-inning Under, I would lean toward the full-game total as well.

Traditionally, pitchers also maintain the edge over hitters early in the season as it is easier for a pitcher to get their arms ready for the season. Now that hitters are taking fewer and fewer at-bats in the spring, it may take longer for them to get the required swings to get their timing down.

I think that will be on par with this matchup.

Guardians vs Mariners game info

Location: T-Mobile Park, Seattle, WA
Date: Thursday, March 30, 2023
First pitch: 10:10 p.m. ET
TV: Bally Great Lakes, Root Sports

Guardians vs Mariners betting preview

Starting pitchers

Shane Bieber (0-0, 0.00 ERA): The 2020 Cy Young Award winner pitched to a 2.88 ERA last season, but the right-hander also possessed the lowest strikeouts per nine innings in his career at 8.6.

Luis Castillo (0-0, 0.00 ERA): Castillo was the ace the Mariners' staff needed. The right-hander had a 3.17 ERA after being traded to the Mariners from the Reds and was outstanding in the postseason.

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Trend to know

The Under is 5-0 in Bieber's last five road starts and 5-1 in Castillo's last six starts overall. Find more MLB betting trends for Guardians vs. Mariners


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