In this week's Nationals Inbox, let's explore the latest on a starting infielder, a familiar face returning and remaining areas of need on the 2021 roster. Have a question for the next Inbox? Send them on Twitter or drop me an email.

How is Starlin Castro?
-- @Brian88847374, via Twitter

Castro was eager to get back on the field as soon as he was sidelined by a broken right wrist last season. Before even undergoing surgery in August, he told manager Dave Martinez, “Just get to the playoffs, and I’ll be back there to help you guys.” The second baseman returned to his home in Miami to rehab, and Martinez described him as “full go” in December.

Castro has been posting videos of his offseason workouts in the Dominican Republic on his Instagram, from taking swings to strength and conditioning drills to … pushing a car.

The 30-year-old Castro slashed .267/.302/.450 with a .752 OPS in 16 games. He played his last game of his 11th season on Aug. 13, 2020.

Do you think the Nationals will sign Ryan Zimmerman for the 2021 season?
-- Ray G., via email

An update: The Nationals re-signed Zimmerman to a one-year contract, marking the first baseman’s 16th season with the team.

The addition of starting first baseman Josh Bell actually accentuated a fit for Zimmerman on the 2021 roster. As a switch-hitter with better left-handed numbers, Bell's addition meant the Nats could benefit from a right-handed hitter to back him up.

Zimmerman, 36, appeared in 85 games in 2018 and 52 in '19 (he elected not to play last season). The plan for 2020 had been for him to be part of a group of veteran infielders who would share first-base duties. Now he is excited to embrace the “called-upon-when-needed” role.

“I train and I prepare myself to play every day, so if something were to happen or if something does happen and I have to start playing five or six days a week, I'll be ready to play,” Zimmerman said on Saturday. “Let me be clear: That's not the plan. … I'd rather play the games that I'm supposed to play and Josh hits 35 home runs.”

Zimmerman hit .257 with six homers and 27 RBIs in 190 plate appearances in the 2019 regular season. Staying clutch, he belted two home runs with seven RBIs in the Nationals’ World Series run.

Are the Nats done with free agency?
-- @HuffyJack, via Twitter

In addition to the question of a backup first baseman (see above), there are other areas of the roster to address. Given that we’re still in January, there’s time to do so.

The Nationals have tasked Yan Gomes with being ready to catch somewhere in the range of 100 games. They still need to determine a backup for the 33-year-old, and his platoon-mate Kurt Suzuki signed with the Angels on Friday. Washington has in-house options in veteran Welington Castillo and No. 17 prospect (per MLB Pipeline) Tres Barrera, but neither is a lock and the Nats could seek another option in free agency.

Washington also could add another reliever in free agency, particularly a left-hander after Sean Doolittle became a free agent. The team signed southpaw Sam Clay in November, and he is looking to make his Major League debut this season. A lefty with experience pitching in late innings would complement the returning group of right-handers Daniel Hudson, Will Harris and Tanner Rainey.

What about the starting rotation, you might ask. There is one spot remaining after the Nationals reached an agreement with Jon Lester (pending a physical) on Monday, and I’d look for them to fill that vacancy in-house. Right-hander Joe Ross has expressed his desire to compete for a starting role, and Martinez has said, “I want Joe to be in the rotation.”