CINCINNATI — The long-awaited major-league debut of Aroldis Chapman turned into a cosmic event Tuesday night at Great American Ball Park. The crowd of more than 19,000 began buzzing as soon as the scoreboard announced that the Cuban left-hander was warming up his 105 mph fastball in the bullpen. When the gate swung open and Chapman began moving his lanky frame toward the mound, the park exploded in a flashbulb-popping, roaring frenzy of anticipation. Any minute, you expected fireworks to explode from the twin smokestacks in center field.

Watching all this, I turned to the guy next to me and said, “What’s the big deal? We’re using to seeing him in Louisville.”

In case you hadn’t noticed, the last three or four years have been the best of times for Louisville baseball fans — better than the early 1980s, when the Redbirds moved in from Springfield, Ill., and better even than the 1940s and ’50s, when the old Louisville Colonels were the Triple-A affiliate of the Boston Red Sox.

In both those eras, the fans in Louisville got to see wave after wave of talented prospects because the Red Sox and St. Louis Cardinals had outstanding farm systems that kept sending big-league prospects through Louisville.

I remember going to Parkway Field in the early 1950s and seeing future big-leaguers such as Frankie Malzone, Harry Agganis, Charley Maxwell and Pete Daley play for the Colonels. The opponents weren’t too shabby, either. The Indianapolis Indians, for example, were Cleveland’s top farm team and they came to town with the likes of Roger Maris, Rocky Colavito, and Herb Score.

In the early years of the Redbirds, then the top farm team of the St. Louis Cardinals, roster was blessed with future big-league stars such as Willie McGee, Vince Coleman, Andy Van Slyke, and Todd Worrell. The Cards won the World Series in 1982, the first year the Redbirds were in Louisville, and made a return trip in 1985.

But Louisville always has been a Reds town. So now it’s different and better than it’s ever been. For the first time since the Bats became the Reds’ top farm team in 2000, the parent team is in the pennant race heading into a September with a team built around prospects developed in Louisville.

I will argue that over the last four or five years, no team in baseball has done a better job of identifying, signing, and developing young talent than the Reds. Everyone in the farm system deserves to take a bow. And in Louisville, manager Rick Sweet, heading for his third consecutive International League manager-of-the-year award, and his staff have virtually been extensions of Dusty Baker’s staff in Cincinnati.

Of the nine players who started against Milwaukee Tuesday night, only Scott Rolen has never played for the Bats. The others were catcher Ryan Hanigan, first-baseman Joey Votto, second-baseman Chris Valaika, shortstop Paul Janish, leftfielder Johnny Gomes, centerfielder Drew Stubbs, rightfielder Chris Heisey and pitcher Adam Harang.

The lineup didn’t include right-fielder Jay Bruce, also a former Bat. Most of the pitching staff — most notably Homer Bailey, Travis Wood, Sam Lecure, and Chapman — also are ex-Louisville stalwarts. At times, so many players have shuttled up and down I-71 that the Reds and the Bats have seemed pretty much interchangeable.

The Reds’ farm system has been so productive that the parent club hasn’t been able to keep all the top prospects. So you see Chris Dickerson starting in center for the Brewers, Jeff Keppinger playing a fine second base for Houston until he got injured, Adam Dunn having another 30-homer season for Washington, and Jerry Hairston Jr. and Chris Denorfia both making significant contributions at San Diego.

After the season, the Reds’ front office will be busy. Votto, a strong candidate for the National League’s MVP, will become a free agent and must be re-signed at all costs. General manager Walt Jockerty must decide which veterans to keep and which to move. A lot of teams will be trying to get their hands on the Reds’ young pitchers.

But now’s not the time for that. Now’s the time to celebrate this exciting team that’s threatending to run away and hide from the Cardinals in the NL Central. It’s also a time to toast the best of all times to be a baseball fan in Louisville.

I didn’t see Chapman in all his appearances in Louisville, but I saw him enough to be amazed at how effortlessly he seems to consistently break the 100 mph mark. I don’t know if he’ll ever be good enough to justify the $30 million the normally conservative Reds threw at him — it’s unlikely he’ll be the next Sandy Koufax — but he could become a consistent 20-game winner for the next decade if he can learn to concentrate for more than a few batters.

His debut couldn’t have been better. Seven of his eight pitchers were strikes. He mixed a fastball that topped out at 103 mph with wicked sliders in the mid-80s. He struck out the first batter he faced — the first of heaven only knows how many hundreds to come — and he caused the other two to tap out weakly to the infield.

Since the pitcher was up first in the bottom of the eight, Baker pulled Chapman for a pinch-hitter, meaning the public got only a tantalyzing taste of what’s to come. But it was enough to make the fans believe that Chapman’s the real deal. For at least this one brief shining moment, he justified the hype.

Over the next month, he’ll sell a lot of tickets wherever the Reds are playing. Already Reds fans are looking forward to seeing him face the Cardinals this weekend in St. Louis. Seeing Chapman handcuff Tony LaRussa’s slumping guys would be almost as exciting as seeing Votto outshine Albert Pujols, his leading rival for MVP (and Triple Crown) honors.

No National Leaguer has won the Triple Crown — lead the league in batting average, homers, and RBI — since Ducky Medwick did it for the Cardinals in 1937. Now, with a month to go, both Votto and Puljos have a shot. And the best thing is, neither has never been linked in any way, shape, or form with steroids. Hopefully, that ugly era in baseball history is over and done.

Now it will be interesting to see which Bats join Chapman and Valaika, who both were called up after spending the whole season in Louisville. I expect to see first-baseman Yonder Alonso, outfielder Wladimir Balentien, and shortstop Zach Cozart called up sooner or later, and I wouldn’t see Balentien play a useful role down the stretch. Right now I’d rather have him at the plate than either Stubbs or Heisey, who both have been woefully inconsistent.

As for Chapman, look for Baker to break him in gradually. For awhile, at least, he will pick spots where Chapman can build his confidence and grow accustomed to the big crowds that will want to see him. By bringing him up before today, Baker made sure he’s eligible for the post-season. Wonder when’s the last time anybody threw a 105 mph fastball in the World Series?

The only way we’re ever going to see Chapman in Louisville again is a rehab assignment. The Cuban missle has been launched and National League hitters should be alerted to begin looking for their nearest fallout shelters.