MILWAUKEE -- The last time the Brewers retired a uniform number was in 2015, when they took No. 1 out of circulation to honor their founder, Bud Selig. That happened just as he was assuming the role of Commissioner Emeritus after a 22-year tenure as Commissioner of Major League Baseball.

How rare was the tribute? Only six men have been so honored, including Jackie Robinson, whose No. 42 was retired across baseball in 1997. No. 1 was the first number retired by the Brewers in more than 15 years, since Paul Molitor announced in an emotional ceremony on July 11, 1999, that should he gain entry to the Hall of Fame, he would wear a Brewers cap on his plaque.

So, here’s the question MLB.com is exploring for all 30 clubs: Who’s next?

• Brewers' all-time retired numbers

Already retired
Here are the six numbers that have been taken out of service in the Brewers’ first 50 seasons:

44: Hank Aaron (1976)
34: Rollie Fingers (1992)
42: Jackie Robinson (1997) -- league-wide
19: Robin Yount (1994)
4: Paul Molitor (1999)
1: Bud Selig (2015)

Those numbers all hang on the roof track high above center field at Miller Park along with No. 50, which is not retired, but was placed there in 2005 to mark radio broadcaster Bob Uecker’s 50th year in professional baseball.

What’s the process?
In short, there isn’t a formal process by which the Brewers decide when to retire a uniform number. It’s an art. But it starts with being in the Hall of Fame; all four of the Brewers players were good bets for Cooperstown when their numbers were retired, and Selig also gained election two years after the Brewers decided to retire No. 1.

When that decision was made, it was driven by principal owner Mark Attanasio, who bought the franchise from the Selig family following the 2004 season and oversaw a series of efforts to honor Selig in 2014-15 at the end of his Commissionership.

“We’ve looked for ways to honor him, because but for his blood, sweat and tears, as well as his daughter Wendy’s, we wouldn’t be sitting here,” Attanasio said then. “We did a statue out front, but it didn’t seem to be enough, frankly.”

Of the players, Yount and Molitor were easy calls. They were the faces of the franchise for much of two decades from the 1970s to the 1990s. Aaron played only two years in a Brewers uniform, but he was baseball’s all-time home run king at the time, and also had deep roots in Milwaukee from his glory years with the Braves before that franchise moved to Atlanta.

The complicating choice was Fingers, not because he wasn’t a great player -- he is one of the best relievers in baseball history, and was absolutely critical to the first two Brewers teams to make the postseason in 1981 and ‘82 -- but because his tenure in Milwaukee was relatively brief. He pitched 259 innings in the uniform over four seasons from 1981-85, and the second half of that time was compromised by an unfortunate shoulder injury suffered at the end of the 1982 regular season.

Yes, he is a Hall of Famer, but others who played for the Brewers and went on to the Hall of Fame have not seen their numbers retired, like Don Sutton, who pitched three years in Milwaukee and logged his 3,000th strikeout in a Brewers uniform, and Trevor Hoffman, who pitched two years here and became the first man in history to reach 600 career saves. In December, former Brewers catcher Ted Simmons was elected to the Hall of Fame as well. He played five seasons for the Brewers.

All hold a special place in Brewers history, but there are no known plans to retire uniform Nos. 21, 51 or 23. All, however, are commemorated via the Walk of Fame and/or the Wall of Honor at Miller Park.

So, who might be next?

Christian Yelich (No. 22)
It all depends on what the coming years look like for Yelich, who signed a new, nine-year, $215 million contract with the Brewers one week before Spring Training was suspended due to the coronavirus. If Yelich can sustain the remarkable numbers he posted in his first two years in Milwaukee -- a National League MVP Award in 2018; a runner-up finish in ’19; back-to-back batting titles; the highest batting average, second-highest on-base percentage and second-highest slugging percentage in MLB; and the third-most home runs over those two years -- then he could be on a path to Cooperstown. The projection systems at Baseball-Reference.com all agree that Yelich still has work to do. The average left fielder in the Hall of Fame logged 65.6 career bWAR and 41.7 bWAR over his seven-year peak. Yelich, 28, so far has a 31.8 bWAR.

“He’s one of the best players in the game,” Ryan Braun said in March. “Obviously, I’m not going to the Hall of Fame. He has a real chance to be the next Brewer to be a Hall of Famer.”

Craig Counsell (No. 30)
Counsell grew up around County Stadium while his dad worked in the Brewers front office, then played six seasons in a Brewers uniform himself and has been in the organization consecutively since 2007 as a player, front office official and now manager. He’s already the only skipper in franchise history to lead the team to multiple postseason berths, and if that success continues through the coming decade, perhaps Counsell would enter the discussion.

Ryan Braun (No. 8)
If making the Hall of Fame is among the unofficial standards for number retirement, then Braun will not qualify, as he said himself last month. But he is a favorite of Attanasio (Braun was the Brewers’ first-ever Draft pick of the Attanasio era in 2005), and whenever Braun retires he will be the franchise leader in home runs and will be top three in hits, RBIs, total bases and OPS. The only men to play more games in a Brewers uniform are Yount, Molitor and Jim Gantner.

Mark Attanasio (No. ??)
This one is for years down the road, perhaps after Attanasio passes the franchise to his sons. Fifteen seasons into his group’s ownership tenure, the Brewers have eight winning seasons, two shy of their number of winning seasons in the franchise’s first 35 years. They have won two division titles under Attanasio, compared to one in the first 35 years. Should a future regime opt to retire a number in Attanasio’s honor, perhaps a fitting choice would be No. 7 for Mickey Mantle, Attanasio’s favorite player as a boy in the Bronx.

Jim Gantner (No. 17)
There exists a segment of Brewers fans who have long clamored for the team to formally honor Gantner, a Wisconsin native who played all 17 of his Major League seasons in a Brewers uniform and was part of the longest-tenured trio of teammates in baseball history with Yount and Molitor before the Yankees’ Derek Jeter, Jorge Posada and Mariano Rivera passed them by. But while the Brewers have not formally retired No. 17, they have not issued it to any player since Gantner retired in 1993.