With addition of Polar Bear, how will O's address first-base logjam?

ORLANDO, Fla. -- With Ryan Mountcastle and Coby Mayo on the roster, the Orioles didn’t need another right-handed-hitting first baseman. With catcher Samuel Basallo on the roster (and expected to get time at first base), the Orioles didn’t need additional options to play first.

But Baltimore couldn’t resist the idea of adding slugger Pete Alonso to the heart of its lineup, as the club agreed to a five-year, $155 million deal with the Polar Bear on Wednesday (according to a source), making a major splash before leaving the Winter Meetings in Orlando.

President of baseball operations Mike Elias made it clear on Monday that positional logjams would not be taken into consideration during the O’s pursuit of an impact bat. He backed up those comments by acquiring Alonso and thrusting him into an already crowded mix.

A lot of questions are now left to be answered once the move becomes official and Elias explains his thought process for how the Orioles move forward from here:

• How many of the starts at first will go to Alonso?
• Is Mountcastle or Mayo (or both) now a trade chip?
• Is there any scenario in which two (or three) of them can coexist on the same roster?
• How does this impact any potential upcoming moves made by the O’s?

Let’s attempt to break it down based on what we know.

Alonso played a full 162 games each of the past two years for the Mets. The 31-year-old has played at least 152 games in every full season of his seven-year MLB career (and he played 57 of 60 in the pandemic-shortened 2020 campaign).

Of Alonso’s 993 career starts, 933 have come at first base, with the other 60 at designated hitter. However, his defensive metrics have regressed a bit in recent years. His minus-9 Outs Above Average ranked in the second percentile in 2025, after he finished with minus-9 OAA (third percentile) in ‘24.

Still, it feels likely the Orioles are bringing in Alonso to be an everyday first baseman.

For one, there’s not likely to be a ton of available starts at designated hitter. Baltimore will want Adley Rutschman and Basallo in the same lineup as often as possible, meaning one will have to be at DH -- unless Basallo starts at first, which now feels less likely with the arrival of Alonso.

Also -- to segue into the rest of the unanswered questions -- Alonso could end up being the only true first baseman on the O’s roster by Opening Day on March 26. The O’s certainly don’t need all three (and won’t have the roster space for all three). Plus, Mountcastle and Mayo could be valuable trade chips, especially the latter.

Mountcastle is a plus defender at first, but it’s also the only position he plays. The 28-year-old’s offensive numbers have dipped in recent years (particularly his power), though he’s also had trouble staying healthy. His homer totals have dropped in five consecutive years -- from 33 in 2021, to 22 in ‘22, to 18 in ‘23, to 13 in ‘24, to seven in ‘25.

However, Mountcastle was limited to 89 games this past season due to a right hamstring strain.

It’s quite possible Mountcastle (who was tendered a contract last month and is entering his final year of arbitration) could bounce back in 2026, setting himself up nicely for free agency next offseason. Maybe another team would want to take a chance on giving him that opportunity.

The more likely trade chip is Mayo, a former top prospect who turned 24 on Wednesday. After coming up through the Minors as a third baseman, Mayo made a full-time move to first in 2025, as his struggles at third made him a better fit across the diamond.

Through 102 big league games over the past two seasons, Mayo hasn’t yet fulfilled his offensive potential, hitting .201 with 11 homers and a .634 OPS. But he finished this past season strong, posting a .301 average and slugging five home runs in 24 September games.

Mayo should garner interest on the trade market. And it would make a ton of sense for the Orioles to move him in their pursuit of starting pitching.

Baltimore has already been linked to potential trade candidates such as Miami’s Edward Cabrera and Washington’s MacKenzie Gore, each of whom would be a frontline starter to insert near the top of the rotation. The Marlins could use a first baseman, so Mayo may be a nice fit.

One thing to make clear, though: The Orioles don’t have to add starting pitching via a trade, as they should still be shopping in the top tier of the free-agent market. Their ownership group has given the front office increased financial flexibility with a willingness to expand payroll (as evidenced by the Alonso signing and other reported offers/interest).

In recent days, the O’s have been linked to free-agent starters such as Framber Valdez, Ranger Suárez and Michael King, and they could still end up signing one of those arms.

Even if Alonso wasn’t needed to fill a hole on the Orioles’ roster, there’s no doubt that his presence will make the team’s lineup much more formidable. It will also open up a lot of possibilities for how Elias will operate -- in terms of what he’ll do with Mountcastle/Mayo and how he’ll go about landing starting-pitching help -- in the weeks to come.