Adam Wainwright is having fun, as expected from a 40-year-old pitcher in a renaissance season. More pointedly, though, he made a decision to have fun six months ago, back in spring training, when his schedule could have annoyed him.

For three consecutive starts, Wainwright, the stalwart right-hander for the St. Louis Cardinals, found himself matched against the same opponent, the Houston Astros. Not a big problem, really, but still inconvenient — repeatedly facing the same hitters, he said, might have robbed him of mystery and led to allowing a lot of hits.

Then Wainwright considered the wondrous possibilities of his job. He throws four pitches — a sinking fastball, a cutter, a changeup and a knockout curveball — and, of course, he can vary their locations. With so many looks at the same hitters, he would overload their internal hard drives and scramble their scouting reports on him. He would toy with them.

Now Wainwright is 16-7 with a 2.88 earned run average across 190⅓ innings. He could pitch in the playoffs for the ninth time in 16 seasons, should the Cardinals (76-69) nab one of the National League’s wild-card spots, and he is standing out as a throwback — the kind of pitcher who believes he has the advantage when facing a team for the third or fourth time through the order. Many teams turn to the bullpen at that point, a reflex that bothers a craftsman.

“When you get to the third or fourth time through, if you’re a , it shouldn’t be that big a deal, honestly, because you’ve got a lot of different ways to get people out,” Wainwright said, in the dugout at Citi Field on Tuesday.

“Now, don’t get me wrong, if I could reach back and throw it 100, I would love to try that. But there’s still pitching behind it. What a great thing it is to watch Brandon Woodruff from the Brewers pitch: he’s throwing 98, but he’s sinking it and cutting it and sliding it and changing it. Man, is that fun to watch.”

This season, batters have hit .227 off Wainwright in his first two times through the order, but just .188 in his third and fourth. He has three complete games and is the majors’ active leader with 27 — not many, historically, but impressive in an era when teams ask so little of their starters. Plenty of pitchers could defy the trend, Wainwright believes, if only they knew how.

“If you can throw that hard, you have so much ability already,” said Wainwright, whose average fastball is 89.1 miles per hour, well below the league average of 93.5, according to FanGraphs. “There’s the ability to be a lockdown, No. 1 starter for a very, very, very long time, if you can learn how to pitch with that incredible stuff. I have to pitch, because if I go out there and try to heave the ball, it’s going to be over quick.”

For most in his role, it is. Major leaguers are averaging only 5.1 innings and 80 pitches per start in 2021, the lowest full-season marks in recorded history. In the 2005 season, when Wainwright made his major league debut, 50 pitchers threw at least 200 innings. In 2019, that number had dwindled to 15.

Even with teams showing more caution this season after a pandemic-shortened 2020 schedule, it is startling to see only three pitchers besides Wainwright — Zack Wheeler of the Philadelphia Phillies, Walker Buehler of the Los Angeles Dodgers and Sandy Alcantara of the Miami Marlins — who have topped 180 innings this year.

The modern emphasis on strikeouts and pitch counts does not lend itself to durability. In 2000, when Wainwright was drafted in the first round by Atlanta, there were 466 games in which a pitcher threw at least 120 pitches. This season, there have been five. Strikeout rates have risen from 6.45 per team per game in 2000 to 8.71 now.

“When you’re striking out a lot of guys, you’re throwing a lot of pitches,” said Dave Duncan, 75, now retired after more than 30 years as a pitching coach, including 16 with St. Louis. “The majority of my coaching career, you started to get concerned around 110, 115 pitches, but you thought everybody should be able to get to 125 without a problem. Well, now you’ve gone from 125 to 110 to 100, and you’re getting your bullpen up when a guy gets into the 80s.”

Wainwright was a borderline power pitcher in his prime, Duncan said, and he averaged more than a strikeout per inning (postseason included) as a rookie reliever in 2006. But even then he had a feel for nuance; Wainwright’s fastball averaged 91.4 m.p.h. that season, blazing for a pitch-to-contact staff, but barely above league average.

This year’s staff is an odd mix: Cardinals pitchers lead the majors in walks while recording the fewest strikeouts. The team plays exceptional defense but has few reliable arms besides Wainwright; only one other pitcher, the left-handerKwang Hyun Kim, has worked 100 innings in a St. Louis uniform.

Yet despite a barrage of injuries, the Cardinals have resisted the use of scripted bullpen days, where several relievers patch together a game. Some of the majors’ best teams, like the Tampa Bay Rays, the San Francisco Giants and the Dodgers, often design games this way. But while the strategy might work — as a way to win games and save money on starters’ salaries — it diminishes a vital role.

“A lot of ideas have been thrown around on how do we get the starting pitcher to be more prominent and last longer, because that’s a draw,” said the veteran Cardinals reliever Andrew Miller, who serves on the executive subcommittee of the players’ union.

“If we’re selling ourselves as an industry and we want as many fans and as many people watching on TV, what’s better: Jacob deGrom versus Adam Wainwright, or an opener and eight bullpen guys versus a guy who is going to finish the season with 117 innings? There’s no doubt it’s the ace pitcher. And it doesn’t have to be just aces. Starting pitcher was always a brand-name position, and we’ve probably pushed away from that a little bit.”

Teams still value the ace; there are seven starting pitchers among the majors’ 10 highest-paid players in 2021. But mid-rotation starters have lost much of their earning power, and with so many hard throwers now, there is greater inventory of interchangeable (and low-paid) pitchers who can get by for an inning or two.

Throwing hard often, for dozens of innings a month, takes a physical toll; the Mets’ deGrom, the majors’ hardest-throwing starter, dazzled for 92 innings this season but has not pitched since July 7 because of elbow trouble. A potential workaround — holding back dominant stuff for just the right moments, to save wear and tear — is easier said than done.

“You hear about that stuff, but not a lot of guys can do that,” said the Cardinals’ Jon Lester, who has eight 200-inning seasons. “I don’t want to say all guys throw max effort, I don’t think that’s true, but I would maybe compare it to hearing PGA guys talk about their swing: they’re trying to be at 90 percent, almost like controlled chaos. So that’s kind of what you want to try to be. There’s times where you try to reach back for more when you have that — but there ain’t really reaching back for anything more now.”

When Lester, 37, was with Boston in 2013, he beat Wainwright twice in the World Series, including a Game 5 duel that was 1-1 in the seventh inning, with both starters still in the game. Back then, Lester said, he threw hard enough to bury cutters inside and go away as a surprise. Now, as he approaches his 200th career victory, he has essentially reversed his game plan.

But while Wainwright has adjusted, too — in concert with his timeless battery mate, catcher Yadier Molina — he is coy with details.

Secrecy matters, Wainwright explained, citing a playoff game a few years ago. Wainwright said he read an article in which an opponent divulged a plan to take Wainwright’s curveball and let it break out of the strike zone. Wainwright dutifully flipped curve after curve into the zone to win the game.

Amateurs often prioritize velocity and spin rate to impress scouts and college recruiters, but to thrive in the long run, Wainwright said, they should master the basics.

“I’ll tell you where it starts: it starts with a game of catch,” he said. “I see so many pitchers now — now — playing fetch instead of catch. A good game of catch is where learning how to pitch really starts.”

And how does Wainwright define a good game of catch?

“You should be able to throw the ball and hit me in the chest, or really close,” he said. “Let’s say I have a hula hoop-shaped target. You should be able to throw within that hula hoop out to a really good distance, and you should learn how to do that. That’s a skill, and it takes practice and it takes a plan. It takes intention. It’s not just throwing to throw.”

Wainwright grew up in Georgia idolizing Greg Maddux, the Braves’ Hall of Fame starter, and internalizing his example. Maddux was a wizard of pitch movement who chiseled the edges of the strike zone, a model of efficiency for more than 5,000 innings mostly for the Cubs and Atlanta.

“He was sculpting it in there, because that’s what it is — we’re artists,” Wainwright said. “Real pitchers are artists out there, and they’re painting their picture as the game goes on. There’s a lot of different ways to get to the end result. Sometimes a hitter makes you do different things, and that’s what pitching is all about — changing speeds, changing angles, changing up and down, in and out, up and in, down and away.

“There’s so much fun stuff there that people are missing by just raring back and throwing the ball as hard as they can.”

Wainwright had carved up the Mets the night before. He lasted only six innings, his shortest start in a month, but it was good enough to win for the fifth start in a row. Later Wainwright trolled the fans, telling reporters with a smile that he used a changeup and two curves to fan Jeff McNeil with the bases loaded — a sly reference to his famous strikeout of Carlos Beltran that clinched the 2006 N.L. championship series at Shea Stadium.

“I like nostalgia,” Wainwright said. “I gave the people what they wanted.”

The funny thing? Nobody even referenced Beltran in a question. That was all Wainwright, still loving his work at age 40, because he knows how to do it in the most rewarding way.