ARLINGTON -- The slider Jonah Heim hit off Royals closer Scott Barlow on Tuesday night was crushed -- and it crushed the Royals on a night they had finally shown some offensive life.

Battling back from a two-run deficit after seven innings against Rangers ace Jacob deGrom, the Royals tied the game in the ninth inning, took the lead in the 10th, had a potential game-saving play from their star shortstop in Bobby Witt Jr., only to see it unravel in a few quick moments.

Adolis García singled on a ball up the middle to tie the game, and Heim deposited a breaking ball left up in the zone 403 feet into the right-field bleachers, handing the Royals an 8-5 walk-off loss in 10 innings Tuesday night at Globe Life Field.

“Got behind and tried to get back on my slider, which probably wasn’t my best,” Barlow said. “I made a good pitch to Adolis, and he got it up the middle. I was more frustrated with that [pitch] more than anything. Really good pitch there. And I just made a bad pitch on the last pitch.”

Heim was 0-for-4 when he came to the plate against Barlow, the Royals’ reliable closer, with three strikeouts and a double-play groundout. Three of those at-bats were against Royals starter Jordan Lyles, who allowed four runs in 6 1/3 innings.

“You’ve got to give them credit,” Royals manager Matt Quatraro said. “Heim had a rough night at the plate, and he put together a good at-bat there and got a good pitch to hit.”

When it mattered most, Heim came through for the Rangers. And for the Royals, it’s hard to avoid key numbers: Kansas City was 4-for-20 with runners in scoring position. They left nine on base.

“If you capitalize and put a crooked number up, it makes it a lot easier,” Quatraro said. “But you got to give them credit for pitching out of it.”

The Royals scored a run in each of the final three innings, but it was the runs they didn’t score that loomed large. And that has been a theme all season. The Royals rank second in baseball in hard-hit rate (47.8%) and rank last in the Majors in batting average on balls in play (.218).

Yet the lineup, which features several young hitters, is slashing .163/.217/.265 with runners in scoring position. And they’re 3-9 this season, on the verge of getting swept in Arlington with Wednesday’s series finale on deck.

“Runners in scoring position at-bats are so volatile,” Quatraro said. “For veteran hitters, too. You always remember the ones that don’t go your way. But there are plenty of them that do come through.

“… You can’t expedite experience. It just has to take time. You can go look at veteran hitters, and they’re going to go through ups and downs of not getting that guy in. Every team feels that way. It just goes in streaks.”

When Michael Massey hit in the top of the 10th inning Tuesday night, he was batting for the fourth time with a runner on third base and less than two outs.

His previous three at-bats were all strikeouts, but Quatraro stuck with the left-handed second baseman against lefty reliever Cole Ragans. This time, Massey came through with a sac fly that gave the Royals a 5-4 lead.

“At that point, just trying to get it done for my teammates,” Massey said. “It’s been a tough stretch, and it had been a tough night for me out there. So really just trying to think of my teammates in the dugout and all the work they’ve put in.”

On Massey’s mind was the eighth inning. The Rangers were leading by a run and intentionally walked Edward Olivares to load the bases with one out. Rangers manager Bruce Bochy wanted the left-on-left matchup for reliever Will Smith against Massey, and it worked: Massey struck out. Nate Eaton, who is 1-for-19 this season, struck out to end the threat.

That’s a learning experience Massey won’t forget.

“When pitchers get runners in scoring position, they seem to find the edges a little more, rip the breaking ball a little better,” Massey said. “Their focus sharpens, and as a hitter, you feel the same way. But there’s nothing like this. You can’t get this in [Triple-A] Omaha. It’s not the same. It’s part of the learning curve. Certainly not an excuse. A game’s a game. You have to come through. There’s nothing that really gets you ready for it except for doing it.”