Rob Thomson blew it for the Phillies when he brought in rookie Orion Kerkering in Game 3 of the NLCS

PHOENIX — Rob Thomson’s had a good run, but nobody’s prefect (wink).

Thomson avoided his veterans, brought in rookie Orion Kerkering, and sped the Phillies to their doom. Craig Kimbrel took the 2-1 loss to the Arizona Diamondbacks in Game 3 of the NL Championship Series on Thursday when he gave up a walk-off single, but his boss lost the game about an hour earlier.

Bryce Harper’s mad dash home on a wild pitch had just given the Phillies the first run of Game 3, so they entered the bottom of the seventh inning Thursday with a 1-0 lead in the game and a 2-0 lead in the NLCS and, as long as they followed their formula, that series lead was likely to grow to 3-0.

» READ MORE: Murphy: The Phillies deserved to lose this one. It took them a while, but they did.

The formula: Seranthony Domínguez or José Alvarado in the seventh, one of the same two in the eighth, Kimbrel in the ninth, and maybe they fly home Friday soaked in champagne instead of Saturday, perhaps high and dry.

In the moment, you thought: Maybe Thomson wanted to invest in the future. Maybe he got instructions from the front office. Maybe he just felt frisky.

Nope. He wanted Kerkering, and Kerkering wanted the ball, and he gave up a quick run and that was that. Momentum lost, game tied, and, soon enough, the series at 2-1.

“He’s pitched pretty well for us,” Thomson reasoned.

“The moment’s not too big for him,” Thomson insisted.

“We knew, in that part of the lineup, there probably were going to be some left-handers pinch-hitting,” Thomson continued. “He’s really good on left-handers.”

That’s true, if irrelevant, since it was two right-handers who smashed hits and scored the run before he faced a left-handed pinch hitter.

To be clear: This isn’t about the kid failing. It’s about his boss not putting him in a position to succeed.

Clearly, in Thomson’s mind, Kerkering had earned this chance to fail. His ascent has been dizzying. He was due for a dip.

A year ago Kerkering, 22, was pitching in college. The Phillies drafted him in the fifth round. Nonetheless, Kerkering was the Phillies’ minor-league pitcher of the year after he rocketed through four levels, from low-A to the majors, in his first full year as a professional, Nuke LaLoosh fashion. Unfortunately, on Thursday, he forgot to wear his garters.

“It felt good. Everything was there, it was just over the plate,” Kerkering said, calmly and softly.

Was the moment different for him?

“No. Same ballgame, whether we’re up 10, down 10, or tie ballgame.”

Was he surprised that he got the call instead of the regulars?

“No, not really. Just be ready for the moment.”

He was willing, and maybe ready, but he was not effective.

After Ranger Suárez and Jeff Hoffman combined for six scoreless innings, and with the entire bullpen rested from the off day Wednesday, Thomson tapped Kerkering. This would be Kerkering’s eighth major-league outing, but only his third of any real importance. In the other two — one in the regular season, one in the playoffs — he entered with at least a two-run lead.

So yes, he’d gotten his feet wet, but yes, this time was different. Kerkering allowed a Tommy Pham single, a run-scoring double by Lourdes Gurriel, and a single by Pavin Smith before Thomson brought the hook.

» READ MORE: Hayes: Phillies bank-busters Harper, Turner, Schwarber, Castellanos money in Game 1 of NLCS

The move cost Suárez a win as he continued a string of otherworldly starting pitching. In nine games, Phillies starters have a 1.72 ERA with 58 strikeouts and just four walks.

Sure, Kimbrel still could have collapsed with the lead. And maybe Domínguez or Alvarado don’t lock it down in the seventh.

They should have had the chance.

Will Thomson go back to Kerkering in a similarly crucial situation?

“Yes,” Thomson replied.

Kerkering is built for it, it seems. Hoffman was there when Kerkering came off the field. There was no discernible change in Kerkering’s poker face.

“Same guy. No difference at all,” Hoffman said. “That’s what makes him great.”

It’s what will make him great, perhaps. But then, consistency is what has made Thomson great, too.

He’s been outrageously effective from the dugout in seven of the nine playoff games, but he’s a big part of the reason they have two losses. Thursday was just the second time this postseason Thomson made a significant mistake.

In Game 2 of the NLDS in Atlanta, Thomson sent ace Zack Wheeler back out for the seventh inning when Wheeler clearly was finished after six. Wheeler gave up two runs and left with a 4-3 lead, but the Braves stole momentum and a win.

» READ MORE: Aaron Nola has earned his millions with two payoff playoff runs. Pay him, Phillies.

Thomson’s virtuosic postseason performance has been the biggest reason why the Phillies locked up the top wild-card seed with five games to play. It’s why they rolled past the Marlins and the Braves with deadly starting pitching. It’s the reason they’ve had historically punishing bats, at least they did until Thursday. Despite 104-degree heat outside Chase Field’s closed roof, the Phillies’ bats stayed as cold as a Pennsylvania autumn. They managed just three hits, two off Diamondbacks rookie starter Brandon Pfaadt (pronounced fought).

Pfaadt entered the season as the Diamondbacks’ top prospect, but in his 19 games he went 3-9 with a 5.72 ERA. He’d been knocked out of his first playoff start, at Milwaukee, after 2⅔ innings, seven hits, three runs, and a homer. His birthday was Sunday, so he’d turned 25 since his second playoff start, and was able to celebrate giving up no runs to the Dodgers in 4⅓ innings. The party continued Thursday: 5⅔ innings, no runs, nine strikeouts, no walks, against perhaps the best lineup the Phillies have ever rostered.

They scored their only run in the seventh, when Harper led off with a walk issued by lefty Andrew Saalfrank, wound up on third with two out, and scored on a wild pitch by right-handed sidearmer Ryan Thompson. That made it 1-0.

That, according to Thomson, was a big enough cushion for the kid.

Except, or course, it wasn’t.

The good news: Don’t expect a hangover. Not from this kid.

A few minutes after Kerkering spoke, Phillies president Dave Dombrowksi glided past Kerkering, who by then was sitting in the clubhouse eating his postgame meal. Dombrowski looked down with a concerned, fatherly frown. Kerkering didn’t even look up. He cut his steak and scrolled his phone.

He’s got the conscience of an assassin and the blood temperature of a reptile, and those are perfect attributes for a reliever. Hoffman’s right: That’s what will make him great.

It’s just that on Thursday, in the biggest moment of his very young career, he wasn’t great.

And that wasn’t entirely his fault.