Nationals ace Stephen Strasburg delivers a pitch to Orioles center fielder Adam Jones on Sunday. Both are starring for upper-division teams. (Toni L. Sandys/THE WASHINGTON POST)

The crowd of 41,918 at Nationals Park on Sunday had barely stopped cheering for Jesus Flores’s fourth-inning homer into the right field bleachers, which gave the home team a 4-3 lead over the Baltimore Orioles, when 10-year-old Micah Hurewitz, standing with his dad in the upper deck, had to start yelling all over again.

On Micah’s back was the name “Strasburg” and at the plate was the same Strasburg, his hero. On an 0-2 breaking pitchfrom Wei-Yin Chen, the Nats star pitcher crushed a drive toward the Orioles’ bullpen, beyond the 377-foot sign in left field. “Get out, get out,” many in the crowd yelled as a strong crosswind tried to knock the drive down.

The O’s Xavier Avery leaped to the top of the fence but was a yard shy of a catch as the 23-year-old pitcher blasted the first home run of his career. If you want the sight line as a historical footnote, Strasburg’s ball was headed toward the statue of good-hitting-pitcher Walter Johnson on the left field concourse. Johnson had 24 career homers along with his 417 wins.

“I don’t think I’ll hit 24 homers,” Strasburg said later, actually smiling, though he was so stone-faced during and after his bomb that teammates had to encircle him, hide him from view and harass him till they made him grin.

Ignited by those blasts, the Nats went on to a crunching 9-3 win over Baltimore, that featured eight Strasburg strikeouts, a two-run Bryce Harper triple and a two-run Danny Espinosa homer to center field.

“The best part of it all was right there — back-to-back!” said Micah, who can’t wait to get back to fourth grade to tease his teacher, an O’s fan, who had advised Micah on Friday to “get out the broom. The Orioles are going to sweep the Nats.”

Not this time, despite exciting 2-1 and 6-5 Baltimore wins on Friday and Saturday nights before comparably huge, and utterly uncharacteristic spring crowds of 36,680 and 42,331 in a stadium with only 41,487 seats. Except on opening day, the Nats have never had a home park crowd as big as any of these three before Memorial Day.

The Orioles have come to town in May four previous times and averaged 86,000 for the three-game series. This series drew 120,929, typical of a spring when Nats crowds are up 28 percent over 2011 after 23 dates. This weekend may have marked the point when the Nats gained traction.

“I was at the Pittsburgh game [Thursday]. We hadn’t planned to come today. Got here, ‘no tickets’ left,’” said Barry Hurewitz, Micah’s father, who lives in the District. (Technically, there were still $185 Presidents Club seats left for the clinically insane.) “So, we got the $20 standing-room-only. I guess we’ve got to get here earlier next time.”

Yep, it looks like there are going to be games where you’ve got to plan ahead if you want one of the 41,487 tickets that come with an actual seat attached.

This is a Washington franchise at a unique moment: growing up before our eyes with multiple generations of fans, old and new. Those who remember the old Senators barely know how to feel when they watch a team that might win a pennant sometime in the next five years.

For them, this is almost hallucinogenic stuff. Is that really Strasburg hitting a homer (and batting .375) and leading the best staff in the major leagues with a 2.93 team ERA? “Best” and Washington in the same baseball sentence? Is Harper, just 19, already semi-comfortable, except for the occasional cover-your-eyes gaffe? By over-hustling, Harper dropped a fly ball that led to two unearned runs Sunday; but, typically, he shook it off and atoned with his triple, a single, a walk and three runs scored.

That gives Harper two triples and two homers this week as the Nats head to Philly on Monday where, the rookie says, “Hopefully, I get a couple of boos up there. That would be awesome. Just so they don’t throw batteries.”

There are also kids like Micah, to whom it’s all fresh and wonderful. “I’ve been a Nationals fan ever since they became a team,” said Micah, who was taken to RFK Stadium at age three. Don’t tell him about Montreal.

But there are many other slices of baseball life here, too, like the 20- and 30-somethings who think a cheap upper deck ticket is actually just a cover charge so they can hang out at the Red Loft bar or hit the picnic benches or the 6,000 “railbird” perches all over the park. They stand in groups, watch the game and keep their food and drinks on a 20-foot-long chest-high bar rail in front of them.

Some days are so perfect that you almost can’t believe your eyes as they transpire before you, even if you hoped they’d come for so long that it almost seemed like forever. On a warm gorgeous weekend, against a first-place Orioles team, that’s what happened on these three jam-packed days. For those who never thought the O’s would be worth watching again as long as Peter Angelos owned them, there is a 27-15 record and promise of better days.

For the 24-17 Nats, on a 95-win pace as MLB passes the quarter-pole of its season, there is hope that, even swamped with major injuries, they may emerge from a tough 33-game stretch of games against AL East and NL East teams (which began with the O’s) with their heads above .500 and their wounded troops returning. Slugger Michael Morse is likely to be back by June 1.

“We’ve got a tough stretch coming up,” said Adam LaRoche, who is hitting .311 and carrying the team with 31 RBI, more than the next two Nats combined. But for now, the Nats aren’t thinking long. They’re enjoying the moment, watching the emergence, the quirks, the mini-milestones of all their young players. Strasburg’s home run trot, for instance, was more of a walk.

By the time he reached second base, he was barely moving forward.

“We’re trying to determine if that was ‘full speed,’ ” said the plodding LaRoche. “He might be the only guy on this team I could beat.”

The Nats and Orioles have three months to go before they can even be considered serious contenders down the stretch this season. But for one packed weekend, capped by a rollicking day, you could see one possible future for baseball hereabouts. And it’s the one we’ve always wanted.

For Thomas Boswell’s previous columns, go to