Well, the Royals sure have a way of throwing left-hander Will Smith into some tricky situations.

Nearly two months after the Royals sent Smith to the mound at Yankee Stadium for his major-league debut against the Yankees, the club recalled the rookie starter on Thursday to face off against Seattle ace Felix Hernandez. It would also be a day game — a predictably sweltering sauna of a day game — and Smith was lugging his 9.00 ERA in three major-league starts up against a pitcher who hadn’t allowed a run in 15 innings.

Well, good luck, Will.

So, yes, Thursday’s assignment — just like in New York — proved to be too much for the 23-year-old Smith to handle. The Mariners escaped Kansas City with a 6-1 victory in front of a shade-seeking crowd of 16,706. Hernandez was his usual King-like self. And the Royals, who lost three of four to the last-place Mariners, dropped to just 2-5 after the All-Star break.

Even worse: The Royals failed to build any momentum after Billy Butler’s walk-off party on Wednesday, and — after losing 13 of their last 17 — are now back to a season-low 13 games under .500 after giving up 31 runs in the four-game series.

“It’s more frustrating than deflating,” Royals manager Ned Yost said. “We’re not pitching well right now. The guys are out giving it their best effort, but we gotta find a way to get back on track.”

There were chances, of course. Eric Hosmer had two hits for the first time since July 5 at Toronto. Salvador Perez raised his average to .377 with two more singles. And the Royals nearly got to Hernandez in the eighth, when Alex Gordon walked to load the bases with one out. But Hernandez bore down, striking out Alcides Escobar before Butler hit a weak grounder to shortstop.

Hernandez worked eight innings, allowing one earned run and eight hits. He was frugal with his pitches too, using just 89 while allowing one run or fewer in eight innings for the eighth time this season.

“He was clearly pounding the zone,” said Royals second baseman Chris Getz, who finished one for three with the Royals’ only RBI. “We may have chased on a few but he’s…coming after us. He’s obviously an elite pitcher and he showed it today.”

So Hernandez’s performance was certainly impressive — before Getz’s RBI single, he’d worked 192/3 straight scoreless innings. But the fact he did it all wearing long sleeves? Now that’s just rubbing it in.

“Always, man,” Hernandez said. “I like to pitch like that — I don’t like to pitch in short sleeves.”

In the end, and considering the circumstances, Smith came away with a decent final line. After getting nicked for three runs in the second, Smith settled down and allowed four runs and eight hits over 61/3 innings. In just the fourth start of his career, he added five strikeouts and two walks while throwing 90 pitches in 100-degree heat.

Still, Smith’s primary bugaboo thus far has been his tendency to surrender the long ball. And that unfortunate habit showed up early on Thursday.

Seattle designated hitter Jesus Montero opened the second inning with a deep blast that just cleared the wall in straightaway center field. (Center fielder Jarrod Dyson appeared to have a good read, but the wall got in the way.) For Smith, it’s now seven homers allowed in just 201/3 big-league innings.

“It was a little up,” Smith said. “I knew he hit it hard, but it just kept going.”

Smith followed the homer by allowing singles to Kyle Seager and Justin Smoak before John Jaso sacrificed them to second and third. The Mariners then struck for two more runs on an RBI single to right from Michael Saunders and a sac fly from Brendan Ryan that required an impressive running catch from right-fielder Lorenzo Cain in the right-center gap.

Meanwhile, the Royals singled twice off Hernandez in the first and second innings — only to watch each scoring opportunity vaporized by double plays.

Smith yielded another run in the top of the fifth when Montero singled home Ichiro Suzuki from third. Suzuki, who once immortalized Kansas City summers with a comparison that’s definitely not suitable for work, had started the rally with a double to left before moving to third on a wild pitch.

The Royals finally scratched out a run in the bottom of the fifth when Getz scored Hosmer on a single to center. It came just moments after Hosmer, who was dropped to sixth in the lineup, doubled sharply to right for his second hit of the day.

The Mariners pushed the lead back to 5-1 with a run against reliever Louis Coleman in the seventh before adding a run against Francisley Bueno in the ninth.

The Mariners just kept scoring all week, averaging nearly eight runs per game during the series, close to double their average for the season. And on Thursday, Hernandez just kept hammering the strike zone.

“He can locate multiple pitches,” Getz said. “He’s got above-average stuff, pretty much across the board. When you’ve got all those tools, it makes it pretty difficult as a hitter, because you can never get too comfortable. How could you?”