The Biggest Mistake the Mariners Can’t Afford to Make This Deadline

Calling Tacoma is not the same as working the trade market.

Dec 9, 2024; Dallas, TX, USA; Miami Marlins president of baseball operations Jerry Dipoto speaks with the MLB Network at the Hilton Anatole during the 2024 MLB Winter Meetings. Mandatory Credit: Jerome Miron-Imagn Images | USA TODAY Sports via Reuters Connect

We are familiar with the routine. An injured player returns, or a prospect gets promoted. Or both. A bench bat, cough, cough, Rob Refsnyder, comes off a rehab assignment. The front office then talks about lengthening the lineup and getting healthy at the right time.

Let’s call the Mariners’ biggest deadline mistake what it would actually be: treating internal reinforcements like external upgrades. Then the trade deadline passes and the roster still has the same hole it had a month earlier.

That cannot be Seattle’s plan this time. Julio Rodríguez returning from the concussion- IL helps. Rob Refsnyder returning and Brendan Donovan working his way back helps. Michael Arroyo forcing his way into the conversation at Triple-A is one of the most encouraging developments in the organization.

Seattle’s Struggles Against Left-Handed Pitching Demand a Trade

None of those developments adds the proven, impact right-handed hitter this lineup needs. Calling those players the deadline solution would be Seattle counting talent it already had as something new.

Arroyo deserves particular attention because the fit is so tempting. He has handled his quick promotion to Tacoma beautifully, hitting .324 with three home runs and a .926 OPS through his first 80 Triple-A plate appearances. He bats right-handed, controls the strike zone and brings the offensive profile Seattle’s lineup lacks.

He also turned 21 this season. The Mariners can promote Arroyo. They probably should if they believe his development is ready for that challenge. They cannot make him responsible for fixing the offense in the middle of a division race. That would turn an exciting prospect into organizational cover.

Let the kid help. Don’t ask him to rescue the lineup because the front office declined to finish the job.

Seattle entered the second half with an MLB-worst .631 OPS against left-handed pitching. Granted, they woke up on July 28 by hitting four home runs off Justin Wrobleski. It’s not enough for opposing managers to change their plan yet. They can stack left-handed pitching, work around the dangerous parts of the order and attack the soft landing spots.

That weakness becomes even more pronounced at T-Mobile Park. Over the past three seasons, the ballpark has carried a 90 wOBA park factor for right-handed hitters, with 100 representing a neutral environment. It suppresses hits, doubles, on-base percentage and runs while increasing strikeouts. Its 2026 numbers have been even uglier, including an MLB-low 89 wOBA factor for righties.

An average right-handed bat can arrive in Seattle and immediately become less dangerous. The Mariners need someone good enough to absorb the ballpark’s tax and keep producing.

Adding an impact bat would change how opponents pitch to Cal Raleigh, Rodríguez, Randy Arozarena and Josh Naylor. There’s a major difference between filling a roster spot and changing a lineup.

We watched the aggressive version of this front office work a year ago. Seattle added Naylor and Eugenio Suárez, won the AL West and came within eight outs of reaching the first World Series in franchise history. Those moves didn’t guarantee anything. They gave a talented roster a real chance to finish the season.

That should be the standard again. Internal reinforcements can support the deadline plan. They cannot become the deadline plan.