If these were normal times, Bruce Zimmermann's big league debut would have attracted a crowd at Camden Yards that “would probably double the normal attendance,” per his brother’s estimation. That’s how deep Zimmermann’s roots run in the Greater Baltimore area, deep enough for Joe Zimmermann to say of their 96-year-old grandmother, Teresa Slade, “she’s been here longer than the Orioles have.”

“I don’t think she’s ever missed a game,” Joe Zimmermann said.

So, there were many who took personal interest in the Orioles' 10-6 loss to the Rays in Game 2 of Thursday’s seven-inning doubleheader, which marked the Ellicott City, Md., native’s Major League debut.

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Zimmermann’s parents, Bruce Sr. and Marcie, watched with Teresa from their Ellicott City home. Joe drove to Towson to watch with cousins who were Bruce’s high school teammates. His sister, Teresa, (Bruce is the youngest of five living siblings) watched from the road to Vermont, where she’ll be married this weekend. Countless others in the Greater Baltimore area tuned in to watch one of their own strike it big: the local kid who made it with his hometown team.

“I remember going down to the ballpark with my brother-in-law and my dad,” Bruce Zimmermann said afterward. “We grew up watching the O’s all the time at night in the summertime. Something my dad would do: He would ask me what pitch was coming next. I remember sitting on the living room couch calling pitches with my dad.”

Then came Thursday, and Zimmermann was throwing them. That was the 25-year-old's main takeaway, even though he did not factor in the decision in what devolved into a doubleheader sweep for Tampa Bay. Allowing five runs in three-plus innings, Zimmermann was imperfect, but he left with a lead that Baltimore's bullpen could not hold.

The left-hander was hurt by homers from Willy Adames and Hunter Renfroe, and he was charged with another run when Travis Lakins Sr. gave up Joey Wendle’s game-tying two-run homer in the fourth. The Rays ran away with things against Dillon Tate later, after the Orioles had rallied on Rio Ruiz’s two-run homer, a two-run double by DJ Stewart and an RBI double from Ryan Mountcastle. Zimmermann called the experience “surreal” anyway.

“I remember Brian Roberts and [Nick] Markakis and J.J. [Hardy] and all those guys, especially in high school when they went to the [2012 American League] Wild Card [Game] and clinched the [AL East] division [in 2014],” Zimmermann said. “Those are my fondest memories with the Orioles, and I’m looking to make more as an Oriole now.”

It’s not that Zimmermann is the first Maryland native to pitch for the Orioles (In fact, they had three on their active roster at different points Thursday, having promoted Zimmermann, Branden Kline and Evan Phillips all on the same day). He’s the 28th Maryland-born player to appear in a game for them and the 12th to start a game on the mound, becoming the first since Steve Johnson in 2012. But Zimmermann's odds were relatively long to make it to Oriole Park.

Overlooked by scouts in high school, Zimmermann went undrafted and cycled through three colleges, pitching for Loyola and Towson before the Braves made him a fifth-round Draft pick out of Mount Olive in 2017. Zimmermann rose quickly, but he was seen as a depth piece in Atlanta's system, an ancillary part of the four-player package that Baltimore received in the Kevin Gausman trade in '18.

Zimmermann reached Triple-A Norfolk in 2019, attended an Elkridge, Md.-based pitching lab in the offseason and, like John Means before him, turned heads this spring by showing increased fastball velocity and considerable polish.

“He’s worked so hard,” Joe Zimmermann told MLB.com in an emotional phone interview. “He was never given anything, you know, his whole career. He was never a prospect. He was never a kid throwing gas. But he was a kid that just worked really hard, all the time, day in and day out.”

It took the Orioles until August to add Zimmermann to their 60-man player pool after he tested positive for COVID-19; his opportunity arose from the circumstances of Thursday’s doubleheader, which came to be because the Orioles decided not to play their originally scheduled game against the Rays on Aug. 27 in the name of social justice. Zimmermann attended a protest in Columbia, Md., following the death of George Floyd at the hands of Minneapolis police officers.

Flash forward a few months, and Zimmermann is the latest in a wave of young pitchers to descend on Baltimore this September, along with Keegan Akin and Dean Kremer. Kremer was solid for the third time in three starts in the O's Game 1 loss. Akin was electric Wednesday night and owns a 3.38 ERA. Together, they look like the backbone of the Orioles' rotation next year, and possibly for more to come.

“It’s still amazing to be on a big league mound, but a little different without the fans there,” Zimmermann said. “Hopefully, it’s something to look forward to in 2021, where guys like Dean and Akin and myself can get a debut 2.0 with our family and friends in the stands.”