DENVER -- “Is this real life?”

It’s the rhetorical question 25-year-old right-hander Darren McCaughan asked himself when he was told he’d be making his MLB debut on Wednesday afternoon against the Rockies. It’s also a question that you probably would’ve heard if you told Mariners fans before the season began that Seattle would be within striking distance of a postseason spot as the Trade Deadline approached.

McCaughan’s boyhood dream became reality Wednesday, and even though the Mariners lost, 6-3, Seattle’s front office will have some tough decisions to make with a club in contention after figuring to be a Deadline seller at the season's outset.

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After the initial jubilation calmed to a quiet exuberance, the reality began to set in for McCaughan -- he’d be making his first big league appearance at none other than the most hitter-friendly park in the Majors, Coors Field. But that didn’t stop him from throwing five hitless innings of relief on a day the Mariners desperately needed such a performance to preserve their bullpen ahead of a homestand that will feature series against the A’s and Astros, both clubs Seattle is chasing in the American League West.

Just 3 1/2 games separate the Mariners (51-45) and the A’s (55-42) as Oakland comes to town. And Seattle is only 3 1/2 games out of an AL Wild Card spot.

“That’s what you play for all year is that these games mean something as we get to the end of July and into August and September,” manager Scott Servais said. “Everybody has to do their part with the ability we have in our ’pen. The guys today, an awesome job, can’t say it enough -- they gave us an opportunity to line up tomorrow. The next couple series are going to be tough, no question about it.”

With Justus Sheffield sidelined by a left forearm strain and Hector Santiago serving a suspension, right-handed reliever Keynan Middleton took the baseball for his first MLB start (as an opener) after coming out of the bullpen in 128 games during his career. He was hit hard for five runs on five hits and one walk in the first inning. McCaughan, who was just called up on Wednesday morning from Triple-A Tacoma, came to the rescue, giving up one run over the next five frames. He walked three, including Sam Hilliard, who came around to score in the fourth on Raimel Tapia’s sacrifice fly.

According to the Elias Sports Bureau, McCaughan became only the third pitcher since the mound was moved to its current distance from the plate in 1893 to throw five hitless innings in relief for his Major League debut, and the first in 54 years. Bill Dillman accomplished the feat on April 14, 1967, for the Orioles against the Kansas City A’s, and Hank Borowy did so on April 18, 1942, for the Yankees vs. the Red Sox.

The lineup was mostly quiet to end the Mariners’ second-half-opening road trip, mustering just five hits, though three of them were solo home runs from Kyle Seager, Luis Torrens and Mitch Haniger. But the loss was of secondary concern. Front and center entering this game were two questions: Who will start? And how will the Mariners piece things together to get through the final game of their road trip?

McCaughan answered that with as good an outing as the Mariners could ask for from a pitcher being thrown into the deep end of the pool -- and the mile-high altitude of Denver -- for his MLB debut. As far as he was concerned, the air was just fine.

“It was kind of like a breath of fresh air once I finally got out there,” McCaughan said. “I think pitching in Spring Training games I was more nervous, just because I expected to play and I knew I was gonna get in there at some point.”

Though he was officially called up on Wednesday, McCaughan had traveled with the team to Colorado just in case he was needed to bolster Seattle’s pitching depth. Having him along for the ride may have given him that last ounce of confidence he needed for his debut.

“I actually came out to the field on the off-day and walked out on the mound and just kind of took in the surroundings of everything,” McCaughan said. “It wasn’t the first time I had seen the stadium. It wasn’t the first time I had been out there. I had taken it in, found my focal point out there in center field, so I felt comfortable on the mound.”

McCaughan doesn’t have overpowering velocity; he’s a sinker-slider pitcher who has developed a good changeup and uses finesse to produce results, as evidenced by his 3.90 ERA in 11 starts between Double-A Arkansas and Triple-A Tacoma this season. Still, he didn’t expect to be in the position he was in on Wednesday -- on a Major League mound.

Then again, the Mariners didn’t expect to be in their current position either. The next few days could determine whether Seattle is a seller or a buyer at the Trade Deadline.

It’s been 20 years since the club was last in the postseason, and what the players and front office do over a 10-day span to close out the month could help decide whether the longest playoff drought in the Majors ends this October.

It is, indeed, real life.