Stephen Strasburg will now make many more starts from the mound at Nationals Park. (Photo by Katherine Frey/The Washington Post)

Sit in the stands Monday night at Nationals Park, watch Stephen Strasburg pitch, and the astute fan might well have looked out and said, “I wonder how many of these starts remain to be seen.” Line up the bits of evidence, and the case that Strasburg would leave Washington after this year would be, in a word, strong: He is in the last year before he would be eligible for free agency. He employs an agent who has signed exactly one pitcher to a long-term deal before allowing other clubs to bid on him. There has been nary a murmur of a negotiations.

And now, he’s staying. Not just staying, but seven years, $175 million staying — unless, of course, he exercises an opt-out clause in the deal.

But put aside that little wrinkle. This is just an eyes-out-of-the-sockets stunner. In surprising developments at a ballpark on an unsuspecting May evening, this has to outdo Strasburg’s major league debut, that 14-strikeout, hello-world epic from 2010 that still ranks up there in terms of an overhyped event somehow exceeding the hype. Yet in a way, we were prepped for that night. Anyone who claims they saw this coming either hasn’t been paying attention or is uttering a bald-faced lie.

So, even as Strasburg struck out 11 Detroit Tigers in what became a 5-4 Nationals’ victory, deep breaths were in order. For a night, at least, let’s not pick apart Strasburg’s deficiencies — the pair of two-run homers he allowed — and consider the deal from both sides, because it is interesting from all angles.

After his seven-inning, four-run outing Monday — “A grind,” he called it — Strasburg declined to comment on the extension, which is likely to be announced at a news conference Tuesday. But he said this much: He is, now, comfortable in Washington, and there was a time in his life when he couldn’t have envisioned uttering such statements.

“Growing up in Southern California — San Diego — all my life and stuff, the East Coast is a little bit of a change,” Strasburg said. “But the city of D.C. has been great to me and my family. It’s really grown on us. We’re very comfortable here.”

That’s what this is about, more than anything: Comfort, on both sides.

For the Nationals: the foundation of the rotation is in place at least through 2019 — the first of two consecutive years in which Strasburg could opt out of the remaining seasons of the deal. Whatever Max Scherzer’s struggles to open this season, the Nationals now have Strasburg and Scherzer as power pitchers still in their prime at the front of the rotation, with low-cost, controllable assets in Joe Ross and Tanner Roark here too, and Lucas Giolito, the top right-handed pitching prospect in the game, on the way sometime soon.

But it also represents another development for the franchise: Not just a willingness to sign the players it has drafted and developed, but the ability to execute such a deal. In the hours before Strasburg took the mound, Jordan Zimmermann plopped himself down in the visitors’ dugout wearing a navy cap adorned with the old English “D” of the Tigers. Zimmermann started more games and threw more innings than anyone to wear a Nats uniform. “I wanted to stay,” he said Monday, but the two sides couldn’t figure out how to come to terms, and he walked. He’ll pitch here Wednesday.

This is, of course, not without risk. At a time when the rest of baseball seemed to be evaluating who Strasburg has become, the Nationals are betting on both his health and his performance.

About that performance: “He’s one of the best starters in baseball,” National League MVP Bryce Harper said. That 14-strikeout debut might just have been the worst thing that could have happened to Strasburg. All his subsequent starts were cast against it. Every slump of the shoulders, every long exhale, has been parsed for years.

Yet since Strasburg’s rookie season, here is a list of pitchers who have thrown at least 600 innings and posted a better ERA than Strasburg’s career mark of 3.07: Clayton Kershaw, Felix Hernandez, Johnny Cueto, Chris Sale, Cliff Lee, Adam Wainwright and Madison Bumgarner. Those seven pitchers, since 2010, have combined for 23 all-star appearances, four Cy Young awards, one MVP and a World Series MVP. Strasburg has averaged more strikeouts per nine innings than any of them and allowed fewer hits and walks per inning pitched than all but Kershaw, Sale and Lee.

This works, too, in the narrow view. In 17 starts since he came off the disabled list last August, Strasburg now has an ERA of 2.26, a WHIP of 0.876 with 150 strikeouts in 115 1/3 innings.

He is, thus, being paid as an elite pitcher because he is an elite pitcher, and he will be just 28 in the first year of the extension.

The deal, though, is at least as surprising from Strasburg’s side. Naturally introverted, Strasburg has been more difficult to decipher than most any athlete in town. We are now in our seventh summer of familiarity with him, but even as he has grown from rookie to veteran, from kid to father, he has only let us in for a brief minute here and there, allowing a quick wipe of the feet on the welcome mat before sending us back out the door.

“His mental state of mind, his calmness, is a whole lot better than it used to be where some of the smaller things don’t affect him as much,” said Dusty Baker, his new manager. “We had a conversation in the spring about that he’s no longer an underclassman. He’s been here a while.”

Strasburg never said he was uncomfortable here. But we were left to guess, and the easy guess was that if his hometown San Diego Padres couldn’t afford him, well, then, the Dodgers and Angels certainly could. These, then, seemed to be our last few months watching this talented curiosity either bloom or wilt.

Now, that time is extended. The Nationals, clearly, expect the full flower. They are comfortable with Strasburg as a pitcher and a person.

Strasburg, though, must feel that level of comfort now, too, both in his clubhouse and his town. This has been a slowly developing, but important, aspect of the story. As one National spoke about Strasburg’s newfound ease with his team and his teammates late last month, he said, “Just good ol’ Stevie.”

Good ol’ Stevie. Wouldn’t it be remarkable if that’s how Stephen Strasburg is remembered here, years from now?