Mayer's starting position has yet to be determined, Jen McCaffrey of The Athletic reports. He played both second base and third base during his rookie season in 2025.

Mayer had been ticketed for a starting role at third base, replacing the departed Alex Bregman, but Monday's acquisition of Caleb Durbin from Milwaukee creates uncertainty. Both Mayer and Durbin have experience at the hot corner and second base in the majors, and manager Alex Cora was hesitant to make any decisions Monday. An early indicator of the infielders' eventual landing spot should come Feb. 15, when Boston's position players report to Fort Myers and where the two are stationed during spring training drills.

Martinez (elbow) hopes to make his season debut by late August, Jack Sommers of SI.com reports.

Recovering from Tommy John surgery that he had last June, Martinez began a throwing program in mid-January. He will continue with a deliberate pace to his rehab and likely begin a rehab assignment a little after the All-Star break if all goes well. Martinez had been serving as the Diamondbacks' closer before getting hurt, but he could retake his old gig late in the 2026 campaign.

Lee is the favorite to start at shortstop for the Twins but must show improved range and more consistent offense, Dan Hayes of The Athletic reports.

Lee took over as the everyday shortstop last season after Carlos Correa was traded, but he struggled at the position defensively. The Twins have very little depth behind Lee at shortstop, so they have little choice but to throw him out there and hope for improvement with the glove. If Lee falters, Ryan Kreidler and Orlando Arcia would be next in line at shortstop for Minnesota.

Ober worked with a specialist much of the offseason after dealing with a nagging hip issue in 2025 and has noticed a "big difference," Dan Hayes of The Athletic reports.

Ober posted a 5.10 ERA over 27 starts last season and saw his average four-seamer velocity tumble from 91.7 mph to 90.3 mph year-over-year. The 30-year-old also lost the command he had been known for, but he is now fully healthy and seems optimistic about a bounce-back season in 2026. Prior to 2025, Ober had a career 3.76 ERA, 1.07 WHIP, 25.6 percent strikeout rate and 5.4 percent walk rate.

Rocker enters spring training as a competitor for a spot in the starting rotation, Kennedi Landry of MLB.com reports.

Rocker broke camp last season in the rotation but experienced an injury and mechanical issues on his way to a 5.74 ERA across 64.1 innings. The 26-year-old right-hander was eventually optioned to Triple-A Round Rock in August and shut down shortly thereafter to refine his mechanics. "Kumar is in a really good spot," Rangers general manager Ross Fenstermaker said. "I think last offseason, maybe, he got away from some things that he needed to do to have success. This offseason, he's gotten back to those things." The organization's acquisition of MacKenzie Gore left one rotation spot available, with Rocker and Jacob Latz viewed as the primary candidates.

Murphy (hip) is expected to be sidelined until sometime in May, Mark Bowman of MLB.com reports.

Murphy had surgery in September to repair a right hip labral tear and is slated to begin running exercises Tuesday. He should stay back at extended spring training while his team his team heads north ahead of Opening Day, with a rehab assignment likely kicking off in April. Once healthy, Murphy is expected to share catching duties with Drake Baldwin.

Atlanta signed Heim to a one-year contract Tuesday, Chris Cotillo of MassLive.com reports.

Heim was non-tendered by the Rangers earlier in the offseason after slashing only .213/.271/.332 across 433 plate appearances in 2025, and his defensive metrics have also declined the last two years. Heim does have a good shot to break camp as the backup catcher behind Drake Baldwin while Sean Murphy (hip) recovers.

Leiter likely has a secure spot in the starting rotation and will not be part of a competition this spring, Kennedi Landry of MLB.com reports.

As recently as two weeks ago, Leiter was viewed as part of a crew competing for two available spots in the rotation. The right-hander, who is entering his second full season with the club, will join Jacob deGrom, Nathan Eovaldi and newly acquired MacKenzie Gore in the Opening Day rotation. Leiter had some rocky stretches early in 2025 but showed improvement over the second half, when he posted a 3.28 ERA and dropped his walk rate to 3.66 BB/9 from 4.4 prior to the All-Star break.

Latz will compete for a spot in Texas' starting rotation this spring, Kenndi Landry of MLB.com reports.

Latz, who served as a swingman in 2025, had a 2.93 ERA over 46.0 innings as a reliever and 2.72 ERA over 39.2 innings in eight spot starts. Those numbers indicate how valuable he was in a dual role; however, the left-hander will be given a shot at being a full-time starter. Latz said in January at the team's Winter Warm-Up that he wants to start, but his ability to excel at both jobs may be more valuable. Kumar Rocker is also in the mix for the final spot in the rotation. Cody Bradford (elbow) also would have been part of competition, but he's not due back until mid-May.

Padres manager Craig Stammen said in late January that Sheets is the team's top option at first base, Annie Heilbrunn of The San Diego Union-Tribune reports.

Sheets' first year in San Diego was mostly a success, as he put up a .746 OPS with 19 home runs, 71 RBI, 57 runs and two stolen bases over 545 plate appearances. The former White Sox slugger made most of his appearances in left field (64 games) and at DH (63 games), but he came up through the minors as a first baseman and has played 92 games there in the majors. It sounds like Sheets is going to enter spring training with the inside edge to be San Diego's primary first baseman, though Stammen has also mentioned Jake Cronenworth, Will Wagner and Sung-Mun Song as options at the position, per 97.3 The Fan. Sheets showed last season that he can be a productive major-league hitter, and if he's able to hold down the first-base role and gain fantasy eligibility there to go along with his current outfield eligibility, he could be a useful fantasy asset this year.