Washington Nationals' Gio Gonzalez pitches to a Milwaukee Brewers batter during the first inning of a baseball game Thursday, Aug. 31, 2017, in Milwaukee. (Tom Lynn/AP)

A young lefty with speed and a fine breaking ball can succeed until he is 30 on that and little more. Then comes the choice. He can pretend he is immune to age and watch his career crash. Or he can learn new pitches, add wrinkles to old ones, use less speed, embrace control, subdue his own ego and maybe pitch forever.

Gio Gonzalez, who turns 32 this month, likes the sound of "forever."

“I want to pitch for another five or six seasons. And I think I can,” said the Nationals left-hander whose 13-6 record and 2.58 ERA, the fourth best in the majors behind only Clayton Kershaw, Max Scherzer and Corey Kluber, have him on the edge of the National League Cy Young Award race.

“Nice season,” I said to Gonzalez recently.

“It’s been a while,” he answered, grinning. But behind that smile was the knowledge that Gonzalez’s annual ERA progression as a Nat would scare anybody: 2.89, 3.36, 3.57, 3.79 and 4.57 last season. With free agency looming after 2018, that’s not the report card you want.

Now, Gio is getting straight A’s. This year, he’s attempted and thus far succeeded at almost every classic, age-appropriate pitching transformation that lefties have been making for a century. But before you can change, you must believe it’s necessary. After last year, Gio did. The agent of that change turned out to be the Nationals’ new catcher, four-time all-star Matt Wieters.

“It’s an honor for Matt to say, ‘I want to work with Gio,’ ” said Gonzalez. “I really appreciate him trying to help me find my way.”

Find his way to where? To the place that left-handers of a certain age have been seeking for a century. The gracefully aging lefty is one of the game’s most beloved prototypes, embraced by fans for his cunning mastery of making great somethings out of pitches that appear to be mere nothings. Only the hitters hate him, muttering, “Oh, no, not him again.”

In 2017, Gio has used more curveballs, more change-ups and fewer fastballs, plus more touch and change of speeds on each of those pitches. More two-seam sinkers have been used for ground balls but are still mixed with enough four-seam smoke at the letters to expand the strike zone. Better command and poise in jams, more focus, yet with an easy vet smile has come from . . . who knows where.

But it showed up right on time: 21 quality starts in 27 games and not one ugly knockout in less than five innings this season.

When he came to Washington in 2012 and won 21 games, Gio just blew ’em away; now, he’s blowing their minds. Less velo, more psycho.

Is it real? Can it last? The Nats know that pitchers of this timing-destroying type provide marvelous counterpoint if your postseason rotation is built around hard-throwing right-handers. Andy Pettitte, Jamie Moyer, Mark Buehrle, Kenny Rogers, Jerry Koosman, David Wells, Jimmy Key and Tom Glavine played that role for decades. Eddie Plank may have invented it while helping the Philadelphia A’s to World Series wins in 1911 (at age 36) and 1913 (38).

Gonzalez’s future could be even better than he thinks. His rubber arm, seldom hurt, has helped him to the seventh-most starts of anyone in this decade.

Since 1900, 29 lefties have won 200 games. How many won more than 100 games after they hit age 32? Answer: 19. Once lefties learn the trick of tormenting hitters, they’re harder to get rid of than termites.

How many of those 29 got most of their career wins from 32 onward, many with an altered style? Answer: 13. Moyer got 218 of his 269 wins after he was Gio’s age. But you never know which way it will go. Sandy Koufax retired at 30. At age 31, Dave McNally and Mike Cuellar were both fine Oriole lefties. But Cuellar bloomed thereafter: 139-75. McNally won only three more games in his career.

Gio has 115 wins. Are there another 115 ahead of him? Who thought Wells would win 176 games, or Rogers 137, after they were Gio’s age?

“This year, Gio has gone from ‘really good’ to one of the elite left-handers in the league,” Nationals GM Mike Rizzo said.

If so, the playoffs can’t get here soon enough. Also featuring Max Scherzer and Stephen Strasburg, the Nationals’ rotation could match any in the game — and there are some brutes now that Yu Darvish is a Dodger and Justin Verlander an Astro.

If not, if the rattled Gio reappears with wild brief outings — he has a 3.93 ERA but only 18 1 3 innings in four playoff starts — then the Nats are unlikely to visit a World Series, much less win one.

In his early Oakland years, Gonzalez threw curves 30 percent of the time; that dropped to 18 percent last season. Now, it’s back up to 25. The change-up, which Gonzalez commands and trusts more each year, is still used 19 percent. But the fastball, which Gio once threw 70 percent of the time, is now down to 56 percent, mostly sinkers.

Finally, Gonzalez says he feels more settled and adult with two young children and a structured home life that adds to his composure.

Oh, did I forget to mention good fortune? There’s some of that, too. Leader boards are awash in Gonzalez’s name. But he’s also top 10 for being lucky, clutch or good at inducing weak contact; he’s never seen so many batted balls go into fielder’s gloves (.249 BABIP) or stranded so many runners (84.5 percent). Some reversion to the mean is due. But not necessarily this year. The whole Cubs rotation had similar good fortune last season.

The young guy who could touch 95 mph with ease, and adored strikeouts, is never coming back. “I don’t have 95-97 (like Scherzer and Strasburg),” says Gonzalez. “But as far as I can go and as much as I can give you, I will be there.”

With “crafty old southpaws,” a term I never thought would apply to the young, goofy, adorable Gonzalez, less and less often becomes more and more with age.

For the Nationals, this version of Gio Gonzalez may turn out to be just enough.

For more by Thomas Boswell, visit washingtonpost.com/boswell