Selected first overall in the 2009 Draft, Strasburg (1-0) allowed one hit while striking out four batters over six innings in the Senators' 10-0 rout of the Portland Sea Dogs to clinch the Eastern League Western Division title.
"We're very excited about the opportunity to play in the postseason," said manager Tony Beasley, who replaced Randy Knorr at the start of the season. "It's been such a joy and a pleasure and I can't tell you how happy I am right now.
"We're not going to do anything different. We take one thing at a time, we'll stay on our routine and stay level-minded. We'll deal with tomorrow when it gets here. I think it's important to go into the postseason with a winning mind. I always tell the guys, 'We have to pedal downhill,' that's what we are planning on doing."
Strasburg, making his sixth Minor League start since returning from Tommy John surgery, was perfect through 4 2/3 frames at Metro Bank Park in front of a record crowd of 8,637. He hit Jeremy Hazelbaker with a pitch, but still faced the minimum through the fifth after Hazelbaker was thrown out trying to steal second base.
Daniel Butler broke up the no-hit bid with a leadoff double to right field in the sixth, but he was erased on Mitch Dening's fielder's choice. No other baserunner reached scoring position.
Pat McCoy threw two hitless innings in the seventh and eighth, and Hassan Pena worked around a leadoff walk in the ninth to seal the victory.
The victory helped the Senators improve to a league-best 79-59, six games ahead of the second-place Flying Squirrels with four to play. Richmond lost, 8-0, at home to New Britain on Thursday, but by topping Portland, the Senators had already clinched the crown, their first division championship since 1997.
Last year, Harrisburg advanced to the playoffs as division runner-up before losing in four games to eventual champion Altoona.
Beasley, who served as the Pirates' third-base coach and took over the reins in Harrisburg when the Nationals made Knorr the manager at Triple-A Syracuse, said he was thrilled with his first season at the helm.
"It's been fun. I've been enjoying myself. It's a great group of guys, the camaraderie has been good [and] it's been great," Beasley explained. "Everyone seems to be on the same page and it's been a joy for me to be in a good environment and work.
"It's been fun to have guys that are capable and have talent. I'm not going to say it was just like old times. It took me a couple of weeks to find the things that I really believed in and were important. I feel really good about the ability to run a ballclub. I'm grateful and honored to have the opportunity."
Beasley has seen productive seasons from a number of his players, but he has also had to manage around injuries and promotions.
Slugging first baseman Tyler Moore, one of just a handful of players to spend the entire year in Harrisburg, leads the team with 30 homers, 88 RBIs and 34 doubles. Outfielder Bill Rhinehart was traded to the Cincinnati Reds at the end of July after smacking 21 homers in 89 games, and top Nats prospect Bryce Harper was lost to a season-ending injury in mid-August after just 37 Double-A appearances.
The club has also had to spend the entire second half of the year without right-handed flamethrower Brad Peacock, who was called up to Syracuse after going 10-2 with a 2.01 ERA and 129 strikeouts over 98 2/3 innings.
"You just have to tip your hat to the guys," Beasley said. "We don't have one guy in our rotation that was in our rotation at the beginning of the year. The guys that have replaced him have done a great job.
"[Pitching coach] Randy Tomlin has done an outstanding job with each guy that has taken the mound, they attack hitters and get the job done night in and night out. We respect the game and play hard at the same time and it seems to be working."
On Thursday, third baseman Stephen King smacked a grand slam, first baseman Tim Pahuta was 2-for-4 with a three-run homer and designated hitter Derek Norris reached base four times and scored three runs.
The Senators will host Richmond or Bowie for the first two games of the West Finals next Wednesday and Thursday.