HOUSTON -- Coming off a season in which they were a game away from advancing to the World Series for the third time in four years, the Astros’ window to contend in the American League remains very much wide open. That will remain true no matter where free-agent outfielders George Springer and Michael Brantley end up in 2021.

Obviously, the futures of Springer and Brantley are the club’s biggest storylines this winter, and general manager James Click will also be tasked with adding some quality arms to the bullpen, acquiring starting-pitching depth and figuring out what to do at backup catcher.

Beyond that, the 2021 Astros will boast cornerstone players in Alex Bregman, Jose Altuve and Carlos Correa, up-and-comers Kyle Tucker and Yordan Alvarez and promising arms Framber Valdez, Cristian Javier and Jose Urquidy, along with veteran pitchers Zack Greinke, Lance McCullers Jr., Ryan Pressly and Joe Smith.

So, what are the five biggest questions facing the Astros heading into 2021?

1. What will the starting outfield be?
The Astros’ starting outfield figures to have at least one new starter next year, with Springer, Brantley and Josh Reddick all free agents. Tucker, who had a breakthrough 2020, while starting 40 games in left, six in right and 10 at designated hitter, is the only sure thing at this point in Houston’s '21 outfield alignment.

Reddick won’t be back, and it seems unlikely the Astros will re-sign both Springer and Brantley. They ranked first and second on the club in OPS in 2020, so losing both would be a big blow to the offense. Re-signing one of them would be a huge boost. In addition to Tucker, the only outfielders currently on the club’s 40-man roster are Myles Straw, who struggled at the plate last season, and Chas McCormick, who has yet to make his debut.

Alvarez is also listed at outfielder, though he’s primarily been a designated hitter in his career. Now that Alvarez has had both of his knees surgically repaired, can he play more outfield next year? We’ll get to that in a minute.

2. Who will be the closer?
Roberto Osuna, the team’s closer who led the AL with 38 saves in 2019, and pitched in only four games in ‘20 after blowing out his arm, is a free agent. Pressly stepped into the closer’s role and did a solid job, but the Astros may opt to bring in an experienced closer next season and let Pressly return to the setup role he’s excelled in while in Houston.

Liam Hendriks, an All-Star with the A’s last season, would be a great addition, but at what price? With so many young arms stepping up last season in relief, including Enoli Paredes, and with Smith set to return after sitting out ‘20, the Astros could bolster their bullpen with one or two relief additions. Among other candidates who would be nice fits are Brad Hand, Blake Treinen, Alex Colomé and Kirby Yates.

3. How will Alvarez bounce back?
After being the unanimous winner of the 2019 AL Rookie of the Year Award, Alvarez was limited to two games in '20 because of knee issues. He underwent arthroscopic surgery on both knees in August, having a slight tear of the patellar tendon in his right knee replaced and a routine cleanup in his left knee. He’s expected to make a complete recovery by Spring Training.

That’s great news for the Astros, considering the kind of impact Alvarez had at the plate two seasons ago. He hit .313 with 27 homers and 78 RBIs in 87 games and hit either fourth or fifth in the lineup that set that the Major League record for highest slugging percentage (.495). Alvarez projects as a 40-homer, 100-RBI player over a full season, and he could fuel a lineup that could be without its top two OPS producers from ’20.

4. Will Altuve, Bregman, Correa and Yuli Gurriel bounce back in the regular season?
The Astros went from having one of the most prolific offenses in Major League history in 2019, to struggling to score runs in ‘20. Houston was a middle-of-the-pack offensive club last season, ranking 14th in runs scored and 16th in OPS.

The drop in production in the regular season by Altuve, Bregman, Correa and Gurriel was a big reason, along with the loss of Alvarez for pretty much the entire season.

Bregman, after finishing second in AL MVP Award voting in 2019, hit .242 last season with six homers and 22 RBIs in 42 games. Altuve hit .219 last season, which is nearly 100 points lower than his career batting average of .311. Correa had a .709 OPS before carrying the club offensively in the postseason. Gurriel slumped badly at the end of the season, hitting .128 with one homer and nine RBIs in the team’s last 34 games, including the postseason.

Several star players around MLB saw similar drop-offs in a disjointed season in which teams played only 60 games in the regular season. Perhaps a longer and more structured regular season in 2021 will allow Houston’s key offensive players to find their level.

5. Is there enough depth in the starting rotation?
Essentially, the Astros lost the top two finishers in the AL Cy Young Award race from 2019 last season after Gerrit Cole signed with the Yankees and Justin Verlander injured his elbow on Opening Day and ended up having Tommy John surgery. Still, Houston's rotation persevered behind a breakout season by Valdez, the emergence of rookie Javier and a strong return to the rotation by McCullers, who missed all of '19 following Tommy John surgery.

As it stands now, the club will enter 2021 with a rotation of Greinke, McCullers, Valdez, Javier and Urquidy, which is enough to compete. Still, they’re on the search for another mid-level rotation arm so the team is better positioned to absorb injuries or underperformance that are almost certain to happen.