Travis Taijeron of the Mets grounds out to shortstop against...

Travis Taijeron of the Mets grounds out to shortstop against the Nationals at Nationals Park on Aug. 26, 2017 in Washington. Credit: Getty Images / Patrick McDermott

WASHINGTON — Travis Taijeron has spent the last three seasons basking in the hitter-friendly conditions of the Pacific Coast League, though until Saturday, his production had done little to vault him from obscurity. Had the Mets’ season gone according to plan, it likely would have stayed that way.

But in a campaign that has long veered off course, Taijeron finally got his long-awaited break, making his big-league debut in the Mets’ 9-4 loss to the Nationals.

“I’m definitely excited,” said Taijeron, before starting in rightfield and going 0-for-4. “It’s been a long journey. I’m pumped up to be finally be up here.”

Starter Robert Gsellman got chased early, allowing six runs, though just two of them earned, in four innings. And closer Jeurys Familia looked rusty while allowing three runs in his first appearance since May 10, just before he was sent for surgery to address a blood clot.

Taijeron, 28, was hitting .272 with 32 doubles and 25 homers with 78 RBIs, flashing the pop that scouts believe is his most valuable attribute. Evaluators also note that he possesses a strong approach at the plate, reflected in his .383 on-base percentage, which has been bolstered by 78 walks.

But that power comes with some significant drawbacks. He has struck out 146 times in 448 at-bats while one scout said he plays only “fringy” defense in the outfield.

Perhaps, evaluators said, Taijeron hits enough to find a spot in the big leagues as a bench outfielder with pop. Or, it’s possible he winds up playing in Japan. Either way, the Mets have time to find out. Taijeron was promoted as Yoenis Cespedes was sent to the disabled list one night after straining his right hamstring.

That left Taijeron to start in rightfield, making him just the 16th player from Cal-Poly Pomona to appear in a big-league game, and the first in 2000. He began his tenure with the Mets as an 18th rounder in the 2011 draft. But until injuries ravaged the roster, Taijeron appeared headed for six-year minor league free agency without ever having gotten a look in the big leagues.

“It’s hard not to get frustrated,” said Taijeron, whose efforts led him to Nationals Park, where the Mets continued the process of playing out the string.

Making his third start since coming off the DL with a hamstring injury, Gsellman paid for a gaffe in the first. Wilmer Difo rolled a one-out grounder to first base. But when he went to cover first, Gsellman dropped the feed from Wilmer Flores, opening the door for the Nationals to take a 4-0 lead in the first. All the runs were unearned.

The Nationals tacked on two more runs against Gsellman, who endured his shortest outing since his return from the disabled list. He surrendered nine hits.

The Mets trimmed the lead to 6-4 in the eighth inning on Flores’ two-run double. But after Kevin Plawecki’s two-out single, Taijeron ended the threat with a broken-bat groundout after coming up as the potential go-ahead run.