Dodgers southpaw Blake Snell called his shot.

It wasn’t quite Babe Ruth pointing from the batter’s box. The moment won’t make its way into any movie. But Snell did tell manager Dave Roberts over text message that he was going to throw six innings in his first start back from the injured list after undergoing surgery to remove loose bodies from his elbow.

Then, en route to a 5-4 walk-off Dodgers victory — courtesy of Max Muncy’s bases-loaded single — in 10 innings against the Royals, Snell did just that.

“I knew that’s what the plan was coming in, and I really wanted to execute that plan,” Snell said after limiting the Royals to one run and three hits.

Despite Snell’s resume, the two-time Cy Young winner wasn’t guaranteed a smooth return. It had been three months since he’d last started a major-league game. And it was only his second start of the season, after a late buildup in spring training due to shoulder fatigue, a May season debut against the Braves, and surgery shortly after.

Eventually getting back this version of him, however, was key to the Dodgers’ postseason aspirations.

“I think the biggest thing was just being aggressive,” Snell said. “Be in the zone, attack. I know how good my stuff is, so I didn’t want to just be nibbling and then complaining like, ‘Oh that’s a strike.’ I didn’t want to do any of that again like I did versus Atlanta.”

That was a short and not so sweet season debut. He exited after three innings, having put his team in a five-run (four earned runs) hole.

The difference Tuesday was “stark,” as Roberts put it.

To clear room on the roster to activate Snell, the Dodgers (72-48) optioned left-handed pitcher Charlie Barnes to triple-A and transferred right-handed reliever Blake Treinen (right elbow inflammation) from the 15-day IL to the 60-day. Though he has not yet begun a minor-league rehab assignment, Roberts said Treinen has not had a setback.

Snell, who had 10 strikeouts Tuesday, kept the Royals off balance all night leaning on a fastball that had a little extra life to it, a curveball that generated a 63% whiff rate, and a changeup that was especially effective against right-handed hitters.

(Eric Thayer / Los Angeles Times)

“I was more calm than I thought I was going to be, so that was good,” Snell said. “But the curveball’s finally coming back to how I remember it being. It was always a pitch that was a wipeout, I could throw it, but now I’m finally releasing it where I need to release it. And I’m kind of releasing everything in the same slot out in front.”

Counterintuitively, Snell pointed to his last rehab start, in high-altitude Salt Lake City, as another factor that helped lock him in for Tuesday. It’s a notoriously difficult place to pitch, with the thin mountain air affecting the way the ball moves.

“To have that start and be that frustrated pitching knowing that I can’t throw anything that I want with any shape,” Snell said, “to be able to come here and just pitch and know I can throw a curveball where I want, whenever I want, and a fastball, that felt way better.

“But Salt Lake was so difficult. Oh my God. If I played in Salt Lake growing up, I don’t know if I’d be here today.”

Roberts set expectations low in his pregame availability, saying the hope was to get Snell through five innings. Snell had other plans.

He struck out the side in the first inning and retired the first 10 hitters he faced.

When he finally gave up back-to-back singles to the Royals’ Bobby Witt Jr. and Jac Caglianone, neither was particularly well struck — a soft line drive and a grounder that found a hole on the right side of the infield.

With runners on the corners and one out, Snell gave up the only run of his start, on a sacrifice fly by Salvador Perez.

The next inning, Snell worked around a leadoff hit — a blooper into shallow right field that speedy Tyler Tolbert stretched into a double — and a stolen base, to strand Tolbert at third.

Back out for the sixth, Snell retired the side in order. He finished his outing by getting Perez to chase a changeup below the zone and pop it up behind second base.

“He was fantastic tonight,” Roberts said. “And you know we pushed him a little bit into the six and through the six, but just because he was so efficient, certainly that extra inning was huge for us.”

It was especially important once the back and forth in late innings pushed the game into extras.

Hard-throwing right-hander Seth Halvorsen tossed a scoreless 10th in his Dodgers debut, setting up Muncy for a walk-off single in the bottom half of the inning.

“That’s the Snell that we’re used to seeing,” Muncy said. “And hopefully we have him for the next two, three months — for the long run.”