Ryan Zimmerman acknowledges the crowd after hitting a walk-off homer in RFK Stadium in 2006. (Preston Keres/The Washington Post)
Sports columnist

Here is Ryan Zimmerman, the realist.

“I’m not an idiot,” the Washington Nationals first baseman said. “Thirty-five-going-on-36-year-olds don’t make $18 million a year anymore. I’m not stupid. But . . .”

There is significance in that “but,” because even a realist has hopes and dreams.

This dreary week, in which baseball diamonds are being blow-torched in hopes of drying them out and players sit around clubhouses wondering whether an impending hurricane will let them ever play again, is as good a time as any for reflection. The Nationals have issues entering the offseason: whether to engage with Bryce Harper, for sure, but also whether to try to extend Anthony Rendon, where to find a catcher and a second baseman, how to augment their rotation and their bullpen. What they don’t have to figure out — what they have never really had to figure out — is what to do with Zimmerman.

Next year at this time, that changes. Zimmerman will make $18 million in 2019, and then the Nats hold an option for 2020 at that same figure. The contract that seemed to extend forever is coming to an end. The realist knows that baseball no longer pays aging veterans that type of money. So he knows, if he is going to finish his career in the only big league uniform he has ever worn, he will have to be healthy. He will have to produce. And he will have to wiggle on what it would cost Washington.

“If I can stay healthy and play next year and still be productive like I am now,” Zimmerman said, “I think there’s room for discussion.”

Production and health will drive that discussion. But with Zimmerman, other factors are hard to avoid.

“He’s the greatest player in Washington Nationals history,” said the man who will be on the other side of that discussion, General Manager Mike Rizzo. If that sounds like hyperbole given the years marred by injury and struggle, consider that Zimmerman has played more games (1,622 entering Tuesday’s scheduled doubleheader at Philadelphia) as a Nat than anyone since baseball returned to Washington. He has more homers (263), more hits (1,727), more doubles (388) and more RBI (981) than any Nat or Montreal Expo.

That “one uniform” thing, it matters. Zimmerman was selected out of the University of Virginia in 2005, the first draft pick after the franchise moved from Montreal. He debuted that September, before he was old enough to legally drink, 20 games in which he smacked 23 hits, including 10 doubles. Not only did he never leave, he never so much as reached free agency. He signed two deals to remain in Washington when Washington didn’t necessarily seem like a nice place to remain. The result: Since Zimmerman’s first full season in 2006, only Yadier Molina of the St. Louis Cardinals and Joe Mauer of the Minnesota Twins have played more games with one team.

Pile on more factors. Zimmerman grew up in Virginia Beach, where his parents still live. His wife was born in the District and grew up in Virginia. The couple lives with their two young daughters in McLean.

If the option for 2020 weren’t picked up, and the Nats weren’t inclined to bring back a 35-year-old at a lower price, would Zimmerman extend his career elsewhere?

“It’s hard for me to imagine,” Zimmerman said. But he has thought about it. He ran into Sean Casey, the former major league first baseman who is now a commentator on MLB Network. Casey played his first eight full seasons in Cincinnati, where he became known as “The Mayor.” But he was traded to Pittsburgh and finished his career with stints in Detroit, where he reached a World Series, and Boston.

“He felt the same way I do,” Zimmerman said. “But he said, ‘Have an open mind a little bit about it.’ ”

An open mind, huh. Ryan Zimmerman of the . . . Texas Rangers? This isn’t exactly Willie Mays-with-the-Mets territory, but it just sounds odd.

Some of this discussion, Zimmerman knows, will be determined by the factor that has most defined his career: health. From 2006 to 2013, Zimmerman averaged just short of 140 games a year. The next three seasons, he averaged just 90 games — ravaged by shoulder, thumb and hamstring injuries — and his on-base-plus-slugging percentage dropped by more than 100 points.

“Health is the main factor for him,” Rizzo said. “When he’s healthy, he’s a middle-of-the-lineup hitter that can still play first base very well.”

This year exemplifies that. Zimmerman nursed oblique and calf injuries in spring training, when he didn’t play in Grapefruit League games. He started poorly. He ended up on the disabled list in May and missed 2 1 /2 months. Since he returned — healthy — he has hit .306 with a .589 slugging percentage and a .980 OPS.

In his past two seasons — including his all-star campaign of 2017, but also his dreadful start this year — his slugging percentage is .550. National League players with at least 800 plate appearances who top that number since Opening Day 2017: Colorado’s Nolan Arenado (.569), Arizona’s Paul Goldschmidt (.560) and Charlie Blackmon of the Rockies (.551).

“For me, it’s about staying on the field,” Zimmerman said. “I’ve got to start sacrificing a little bit — whether it’s the way you run the bases, how you play defense — to stay on the field and basically be a hitter. I can’t be sliding headfirst in a 6-3 game trying to go first-to-third in the fifth inning. You have to understand situations.”

He is 2½ weeks from his 34th birthday, and he understands his situation. Harper’s free agency has hung over the Nationals for at least two seasons. Zimmerman’s never has. He pledges it never will.

“At this point, it’s not about money for me,” Zimmerman said. “I’ve made more money than I could ever imagine, than I could ever spend. For me, it would be about continuing to play here, liking playing here, and kind of finishing what you started — winning. I think we’re set up to be pretty good.”

At his house, Zimmerman has a closet in which he keeps jerseys and memorabilia he has collected over the years. Occasionally, when he is fishing for something else, he will stumble upon an old Nats jersey from that 20-game debut in ’05 — “ZIMMERMAN” across the back, but No. 25, not the 11 he has owned since 2006.

“It’s not even the mesh kind,” he said. “It’s the old heavy one.”

Gets you thinking about how long you’ve been around. Eleven walk-off homers, including the shot that opened Nationals Park. Gold Glove-caliber third base before his shoulder succumbed, making each throw perilous. Seasons in which he appeared done, only to be followed by rejuvenation. Now, two hours of daily work on his body just to be able to play a game. He has never been a controversial quote. It doesn’t mean he is without war stories.

“You know me,” he said. “I don’t really get caught up in that stuff very often while I’m still in it. But I’ve started to. In the offseasons now, I’ll spend some time with buddies. They’ll start talking, and you have a couple beers, and you start talking, and you start telling stories. It’s like, ‘Man, it’s pretty cool. I’ve got a lot of stories.’ I wouldn’t have guessed that.”

Next season will be Zimmerman’s 15th as a National. He is not an idiot, so he knows a 16th isn’t guaranteed. He is the last Nat from the inaugural season. Can anyone, including him, imagine him retiring as something else?