Buster Posey tried to watch every inning of San Francisco Giants baseball that he could last year, but he was busy.

Most of his energy was spent caring for four children, particularly two adopted twin girls who were born eight weeks premature last summer. But he also found a useful way to keep his arm in shape -- by balling diapers up really tight and flinging them at his 9-year-old son, Lee, while he ran for cover.

"You have to really make sure that you have the right weight of the diapers," Posey said after the Giants' first official workout on Wednesday. "Depending on how well they've been feeding, that plays a lot into my accuracy and if it's equivalent to the weight of a baseball. Take all that into account, whatever type of formula they've got, if they're eating baby food or not -- and yeah, I've been pretty accurate."

Posey, who sat out the COVID-19-shortened 2020 season primarily out of concern for his newly adopted daughters, heads into the 2021 season with unfamiliar uncertainty. By Opening Day, he'll be 34 years old, entering his 11th and potentially final season as the Giants' everyday catcher. Posey's $167 million contract includes a $22 million club option for 2022, but the Giants also possess a promising young catcher in Joey Bart, who was drafted second overall in 2018 to someday replace Posey long term.

"Yeah, sure, it's gone through my mind," Posey said of the possibility that this might be his final season with the Giants. "I think, for me, my biggest goal this year is really to -- as cliché as it is -- go one day at a time and try to focus on what needs to be accomplished for that day, whether it's stuff in the weight room or cage work or whatever it may be. And try not to get too far ahead."

The last time Posey was on the field, he was coming off hip surgery and struggling through the 2019 season, ultimately batting .257/.320/.368 with seven homers and 24 doubles in 114 games. In seven prior seasons, he made six All-Star teams, won an MVP Award and batted .308/.378/.466 while averaging 16 homers, 31 doubles and 141 games per year.

Giants manager Gabe Kapler stated in the middle of December that Posey would return as the team's primary catcher in 2021, offering the 24-year-old Bart more time to develop after a trying season in 2020.

Posey had access to Oracle Park when the team wasn't there last summer and utilized the facilities to train routinely. He admitted that it might take him some time to get re-acclimated to live pitching but believes his body is in good enough shape to stand up to the rigors of another season. He missed the competition.

"It's nice," Posey said of returning to play. "It's different. Look at what we're doing right now [conducting an interview over video conference] -- it's not the same. You're still in masks, so that's obviously different as well. There's normalcy, too. There's the normalcy of standing on the foul line and stretching. Playing catch, catching 'pens. Yeah, it's great to be back, and hopefully as this vaccine continues to roll out, we'll be able to all get to experience the game like we're used to."