When Marcus Semien walked off the field at Dodger Stadium following the A’s elimination from the postseason in Thursday’s 11-6 loss to the Astros in Game 4 of the American League Division Series, he wondered if that might be the end of his time with Oakland.

Semien, Oakland’s longest tenured player, is set to hit free agency for the first time in his career this offseason. Since joining the A’s in a 2015 trade with the White Sox, the 30-year-old shortstop has made vast improvements to his all-around game. An unquestioned team leader, Semien finished the 2019 campaign third in the AL MVP Award voting and ended the 2020 postseason as one of the club’s top hitters.

“He and I ended up talking a lot over the course of this season,” A’s general manager David Forst said. “We’ve had an open line of communication with him and his agent for the last year, and I think everybody knew we would get to this point. This will certainly be one of the topics for this offseason.”

But Semien’s value goes beyond what he's brought on the field for the A’s. His presence in the clubhouse has molded the winning mentality that has been instilled into the club’s younger stars like Matt Chapman and Matt Olson. A Bay Area native, Semien has also played a major role in the city of Oakland with his involvement in numerous community programs.

“I haven't thought about that yet,” A’s manager Bob Melvin said of Semien’s impending free agency. “I’m pretty close to Marcus, so we'll be in close contact here. I wish him the best in whatever happens. Obviously, we'd love to have him back.

“He's meant so much to this organization, not only as a player but as a person and as a leader. What he means to the community. There are a lot of reasons that we would love to have Marcus back.”

Though Semien’s regular-season numbers did not stand out in 2020 -- he slashed .223/.305/.377 with seven home runs and 23 RBIs over 53 games -- the shortstop went on a tear once October hit. Semien led the A’s with a .407 batting average over six postseason games and provided a spark at the top of the lineup.

While Semien said he would love to end his career playing for his hometown team, he also realizes there is a business side to all this. Playing a premium position, there should be no shortage of lucrative offers from other teams vying for his services. That’s why the thought of this possibly being his final season with the A’s has crossed his mind several times the past few weeks.

“I’m pretty logistical. I understand what’s going on with everything,” Semien said after Game 4. “Our backs were against the wall a couple of times here in the playoffs. You put that jersey on and take the field, I took the field in the bottom of the eighth and was like, ‘Is this my last time playing shortstop for this team?’ I don’t know.

“I’ve never been in this position. I’ve always been with Oakland and before, with the White Sox. This is new to me. I haven’t taken that much time to think about all that, but that was pretty much what I was thinking in the bottom of the eighth.”

Semien is just one of several impending free agents from this 2020 A’s club, and most of them played a key role to their success. Among those players are Semien’s double-play partner Tommy La Stella, as well as outfielder Robbie Grossman and pitchers Liam Hendriks, Mike Fiers, Yusmeiro Petit, Jake Diekman and Joakim Soria.

If Semien signs elsewhere, the A’s do have a potential in-house replacement option with Nick Allen, Oakland’s No. 4 prospect per MLB Pipeline. Though Allen has yet to play above Class A Advanced, he's considered one of the top defensive prospects in the game, with a glove that appears to be MLB-ready. His defensive prowess would make for quite the duo on the left side of the A’s infield, with the Platinum Glove Award winner Chapman at third base.

La Stella made a huge impact in a short stint. Joining the A’s in a trade from the Angels on Aug. 28, La Stella established himself as Oakland’s everyday leadoff man, batting .289 over 27 regular-season games and .291 in six postseason contests.

“[La Stella]'s the kind of guy who, when you're playing against him, you think you have a sense of how good of a player he is. Then when you see him every day, you really appreciate the things he does,” Forst said. “I thought what he brought to the lineup in the last month of the season after arriving was critical in getting us to where we went.”

Potential options already on the club to replace La Stella would include Tony Kemp and Chad Pinder, who could move back to second base after filling in at third after Chapman underwent season-ending hip surgery in September.

As for the pitching, the A’s have talented depth in the Minors that could help them withstand some losses via free agency, though it would be hard to imagine where Oakland would've been this season without the dominance Hendriks provided as closer. The A's went 23-1 when the 2019 All-Star made an appearance.

If Hendriks signs elsewhere, Oakland will likely take a look at available relievers in free agency. Options on the current roster might include Lou Trivino or Jordan Weems, with No. 1 prospect A.J. Puk a bit of a wild card if the club were to decide to convert him into a reliever given his recent string of injuries.

There will certainly be no shortage of intrigue this offseason for Oakland. It’s rare that any team can re-sign all of its top free agents, though Semien could be a top priority.

“Marcus is an incredible person. As a friend, as a teammate, as a man, you can’t have a better teammate than Marcus,” A’s outfielder Mark Canha said. “You look at how consistent he was in the playoffs despite his numbers in the season. He had injuries and hardships this year, but he’s just a fighter and the ultimate guy you want on your team and I sure hope we get him back.

“I don’t think that’s lost on anyone in our organization or anywhere else. Marcus is going to be just fine. He’s our captain."