Alex Bregman signing with Cubs opens the door for Marcelo Mayer at third base with Red Sox
With Bregman off the board, Boston weighs internal options, trade scenarios, and the long-term fit of Marcelo Mayer at third base.
Alex Bregman is officially off the board — and with him goes Boston’s clearest answer at third base.
Bregman agreed to a five-year, $175 million deal with the Chicago Cubs on Saturday night, a contract that includes no opt-outs and a full no-trade clause. The move leaves the Red Sox with a glaring vacancy at the hot corner as viable external options continue to thin out.
With the offseason marching on, Boston’s best solution may already be in-house.
One player who could open the season as the Red Sox’s starting third baseman is Marcelo Mayer.
The 23-year-old has spent the offseason taking reps at both second base and third base, preparing for a scenario in which Bregman moved on — a scenario that is now reality. Mayer made his major-league debut last season and started 35 games, 28 of them at third base and seven at second.
Boston promoted Mayer from Triple-A Worcester after Bregman landed on the injured list with a right quad injury, and the former top prospect quickly showed he could handle the defensive demands of the position.
“It’s not easy going into an offseason kind of getting reps at every position,” Mayer said at Fenway Fest on Saturday. “I believe that every position requires different traits, different skills, different angles that you need to master. Obviously, I’m doing everything I can taking reps at third and second base and I feel really good at both.
“So wherever they need me is where I’m going to play. I’m going to do my best out there.”
Mayer is still viewed as Boston’s long-term answer at shortstop, but with Trevor Story under contract, the Red Sox are comfortable deploying Mayer off-position for now.
Mayer also explained the differences between second and third base.
“Second base, you’re doing everything backwards,” Mayer said. “Third base, you’re pretty much playing shortstop with less range — quicker reflexes. They’re just different skills you need to hone to be great at that position.”
There are alternatives on the market, though none come without drawbacks.
Free agent Eugenio Suárez is coming off a massive offensive season, blasting 49 home runs between the Diamondbacks and Mariners. However, the defensive cost would be significant for a Red Sox team that has already struggled in the field.
In 2025, Suárez posted -6 Defensive Runs Saved and -3 Outs Above Average, continuing a multi-year trend of below-average defense. Adding another liability at third base would run counter to Boston’s stated goal of improving run prevention.
Another possibility: Craig Breslow could pick up the phone and call an old friend.
The Red Sox and Cardinals — now led by former Boston chief baseball officer Chaim Bloom — have already completed two trades this offseason. Boston has been linked to Brendan Donovan, and it’s hard to believe Nolan Arenado’s name hasn’t resurfaced in conversations.
Arenado’s contract is far more manageable than it once appeared. He is owed $27 million in 2026 (with $5 million covered by the Rockies) and $15 million in 2027. St. Louis, firmly in rebuild mode, is motivated to move the deal and would almost certainly eat salary to facilitate a trade.
Arenado also holds a full no-trade clause — and is reportedly eager to leave as the Cardinals pivot toward a youth movement.
For Boston, the appeal is clear: a short-term commitment to a still-elite defender at third base. If Arenado were acquired, Mayer could slide to second base, allowing the Red Sox to lean into their young core while supplementing it with a proven veteran.
While the Red Sox’s pool of upper-level positional prospects has thinned, they still have pieces to move. Mikey Romero, Franklin Arias, and Henry Godbout represent the next wave, giving Boston flexibility if they choose to deal from that group.
If the Red Sox opt to keep things internal, much hinges on Mayer’s durability.
He’s coming off wrist surgery but is expected to be fully healthy for spring training.
“I’m pretty much doing full baseball activity — a normal ramp-up like I would for a regular season,” Mayer said. “I feel like I’m in a good spot.”
Still, Mayer has seen each of the last three seasons end due to injury. While he hasn’t earned the “injury-prone” label yet, another shortened year would put that reputation in play.
To help prevent that, the Red Sox asked Mayer to add strength this winter. He’s answered the call.
“It was one of the main goals I set for myself going into the offseason,” Mayer said. “I weighed in at like 218 right now — by far the heaviest I’ve ever been. I feel great, stronger and faster than ever. My body’s in a really good spot.”
Whether Boston fills third base internally with Mayer or makes a final push for external help, the Bregman miss has forced their hand. The Red Sox still have options — but none without risk.
What they choose will shape not only their 2026 lineup, but the future of their infield core.
