"It's up there with the best pitches in baseball," catcher Brian McCann said. "The numbers don't lie. He's got a great feel for it."
McCullers allowed three runs on four hits and four walks over 5 1/3 innings, earning the victory in the Astros' 5-3 win Friday night.
The Astros now hold a 2-1 lead in the best-of-seven Series, with the next two contests at Minute Maid Park, where Houston is 18-2 in its last 20 games.
The curveball rate -- McCullers threw the pitch 62.1 percent of the time -- was the highest by a starter (minimum 50 pitches) in any regular-season or postseason game since pitch tracking began in 2008.
McCullers, who battled back discomfort and arm fatigue during the final two months of the regular season, has rebounded in a big way during the past 10 days. He allowed one run over 10 innings in two American League Championship Series appearances against the Yankees, earning a win in Game 4 and a four-inning save in the Game 7 clincher.
The curveball has been the key to that success, yet after he finished off the Yankees with 24 straight hooks in Game 7, McCullers came out firing fastballs on Friday night, throwing five straight heaters to Chris Taylor to start the game.
After a pair of quick scoreless innings by McCullers, the Astros erupted in the bottom of the second, batting around for a 4-0 lead.
The 22-minute inning may have affected McCullers' rhythm, as he promptly walked the first two Dodgers in the third. His leash appeared to be short; Brad Peacock began warming up in the bullpen as pitching coach Brent Strom went to the mound for a conference.
"It just looked like he fell apart mechanically, and just his command fell apart, three walks in a row, and he created his own mess," manager A.J. Hinch said. "I don't know if it was the layoff with the big inning or if it was just some poorly executed pitches, but we just wanted to settle him down."
McCullers, who said he "didn't have much tonight from the get-go" and struggled to locate, issued a third walk after Strom's visit to load the bases for Corey Seager.
"After a big four-run inning from the guys, you don't want to change your approach for the team, because that's the easiest way to get in trouble," McCullers said. "But I stuck with mine, and I just didn't land pitches, which is the biggest thing. I don't really attribute it to anything else, I just wasn't executing at the time.
"That situation, or any situation, you're one pitch away," McCullers said. "You're one executed pitch away from a double play, like I ended up getting, or three good pitches away in a row from punching a guy out and kind of alleviating that situation a little bit. So you can't sit back and look at it and say, 'Oh my goodness, I have three guys on and I have the core of the lineup up,' or you'll crumble. You have to continue to try to make your pitches."
"He was in and out of the zone, had a good curveball tonight, had us off balance tonight," Seager said. "We couldn't scratch anything off him."
McCullers rediscovered his command in the fourth, throwing nine of his 11 pitches for strikes. He also benefited from Carlos Correa's strong throw from shallow left field to nab Yasiel Puig, who was thrown out at second base on what otherwise would have been a double.
In the sixth, with the lead boosted to 5-1, McCullers issued a leadoff walk to Seager as Peacock and Francisco Liriano started getting hot in the 'pen.
McCullers struck out Cody Bellinger for the third time, puzzling the rookie with his curve. Bellinger registered four swings and misses against the pitch, the same number as the Dodgers' other eight hitters.
"He pitched to my aggressiveness," Bellinger said. "I was out of whack today, and you have to give him credit. He spotted the curveballs where he wanted to, and if he hung it, I didn't do damage. That's just how baseball rolls."
That was McCullers' final batter, as Peacock relieved him with one out in the sixth. Puig's RBI groundout and a wild pitch by Peacock allowed both of McCullers' runners to score, boosting his final pitching line by a pair of runs. Peacock made it up to him, retiring nine of 10 batters to end the game and lock down McCullers' win.