Red Sox back-up infielder (Bobby Dalbec, Enmanuel Valdez, or Yu Chang)
Bobby Dalbec seemed like a lock to make the Opening Day roster. Triston Casas is likely to start out the year as the team's starter at First Base, but in the event of an injury or cold stretch, Dalbec should be ready to fill in for the rookie. Then the Red Sox signed Yu Chang to a major league deal, which seemingly gave him the final spot. There is, however, the chance the Red Sox opt to go with Enmanuel Valdez.
Valdez was acquired from the Houston Astros at the 2022 Trade Deadline for Christian Vazquez. He cooled down when he joined AAA Worcester, but in 126 games between AA and AAA last season, Valdez hit .296/.376/.542 with 28 home runs and 35 doubles. He also saw playing time at 2B, 3B, and LF, so the versatility could get him playing time at a few different positions. With the middle infield picture being unclear - current options including Kiké Hernández, Christian Arroyo, and Adalberto Mondesí - Valdez could make the jump to the majors right out of spring training.
There's a new wrinkle in the picture, however. The Red Sox re-signed INF Yu Chang to a major league deal; signing him makes sense as the Red Sox lack Triple-A depth at middle infield, but a major league deal should get him on the major league roster, barring a surprise. Alex Cora says that Adalberto Mondesi may not be ready for Opening Day (per Chris Cotillo of MassLive), so Chang offers insurance alongside Kiké Hernández and Christian Arroyo.
The question may not be who makes the opening day roster, but instead, what happens to Bobby Dalbec? Dalbec was available for trade earlier in the offseason, per Sean McAdam, and the Red Sox could re-explore trade talks this spring. Dalbec plays first base, which could be important if Triston Casas misses any time, but the Red Sox could be convinced to move on from Dalbec if there's significant trade interest.
Dalbec is 27 years old, coming off of a poor 2022 season, and still has two options remaining. He seems to be likely headed for AAA to start the season, though a trade could still happen. As for Valdez, he'll be the next man up if anything happens to Chang.