Now, every time someone has stalked or reached 300 wins, the question has been raised as to whether he will be the last of the breed -- a contradictory exercise to say the least.
But this time, the sky really could be falling.
It's quite basic:
When Roger Clemens pulled into the 300-win club on June 13, 2003, Greg Maddux sat on 278 wins.
When Maddux crossed the threshold on Aug. 7, 2004, Tom Glavine had 259 victories, also in the neighborhood.
And when Glavine got his 300th on Aug. 5, 2007, Johnson was at 284, although gripped by a recurrence of his back woes.
But as Johnson pulls into the destination, there is no active pitcher on his trail.
The pitcher closest to him is Jamie Moyer, with 250 wins. And considering 35 days lapsed between his 249th and 250th wins, the 46-year-old's career doesn't have enough shelf life to sniff 300.
As for the younger set, we're looking at 36-year-olds Andy Pettitte and Pedro Martinez, at 220 and 214 wins, respectively.
Active wins leaders
|* Free agent|
And neither is a Big enough Unit to pose a threat.
So hopefully you enjoyed Johnson's ride into a glorious sunset, because it's a tale you could be relating to disbelieving grandkids.
"Pitching 271 innings? Winning 24 games? Striking out 372 people? C'mon, who are you kidding?"
Any more 300-game winners upcoming? Who are we kidding?
"I don't think there will be one for a while," said Nolan Ryan, who bagged his 300th in 1990 with the Rangers, whom he now serves as club president. "A lot of it depends on changing the way pitchers are used now. It's not the five-man rotation as much as starters not going deep into the game, and the fact that they use as many as three bullpen guys.
"When the starter goes out, the more bullpen guys you use, the better chance you have one of one them having a bad night. I don't think [the 300-win club] is like the 500-home run club, where you have a lot of guys moving into it. There are a lot less 300-game winners."
"You don't want to say never, but this could be it, with Randy," Glavine said. "It wouldn't surprise me if there's not another.
"We're not developing 250-, 270-inning pitchers. When you throw 250, 270 innings, it gives you a better chance to get a win. It's tough to get a bunch of wins if you're going five or six innings. There are many pitchers who have the talent to win 300 games. But I'm not sure you're going to see the durability you saw a generation ago."
With a little better support from the Arizona lineup and bullpen, Johnson would have had his 300 wins long before this. Once recovered from back surgery, he offered a flashback in the second half in 2008: a 2.41 ERA across 13 starts and 86 innings, in which he struck out 76 and walked only 16.
But only five of those starts resulted in wins. Five other times he pitched six-plus innings on a yield of three runs or less, and the D-backs lost all five.
"I feel bad in some regards -- that I've done a lot in Arizona, it would have been fitting to do it there," said Johnson, a native of Livermore in the Bay Area. "But I also feel like this is the next-best scenario, coming back [home].
"I'm familiar with the ballpark, I'm familiar with the Bay Area. It's where I grew up. It's as good a last chapter of my career that there could be."
Johnson's affection for AT&T Park is understandable -- his first four wins this season came there, improving his career numbers by McCovey Cove to 7-4 with an ERA of 3.02 in 13 starts.
So how appropriate for his legacy is win No. 300 being not only his first of the season on the road, but first ever in Washington, D.C.? Nationals Stadium became the 41st Major League park in which he has rung up a victory.
Unlike many other athletes of his stature, Johnson is acutely aware of his 21-season accomplishments and sensitive to those who, innocently or not, slight them. For example, those who see his age-induced drop in velocity as a sign of diminished skills.
As Johnson himself said, looking ahead to when he views his career in a rear-view mirror, "I'll say it was fun when I was throwing 98, but more of a challenge when I was throwing 91-93. I'm the majority now. I'm not the minority anymore."
Stuff-wise, perhaps. But when it comes to competitive drive, few have ever been able to keep up with the 6-foot-10 left-hander, whose game face could be the warning label on cans of rat poison.
"My drive to come back and pitch after the back surgeries has been fueled by knowing that I can still pitch at a high level," Johnson said earlier this spring. "People say that I've just come back to win 300 games, but that's not the case. If you're 45 or 46 years old and still pitching at a high level, why would you want to retire?"
And he's not just talking about now, but also the foreseeable future.
"Who's going to dictate whether I retire or not, other than me?" he said. "I mean, there have been times when I thought my career was fleeting. My fastball was gone, but being completely healthy now, I still have that drive to succeed, and I'm not going to end on 300 wins."
But 300 wins may well have ended with him.