Walker Buehler had everything under control Tuesday night. He was mowing through another big league lineup in his path, leaving the Arizona Diamondbacks in search of answers. Three batters had reached base through five innings. The Dodgers’ 1-0 lead seemed bigger than it was with him on the bump.

Buehler continued his plowing in the sixth inning by quickly inducing two flyouts to begin the frame. His pitch count read 67. An end to the rookie’s dominance did not appear in sight. Then he faltered. First, Jon Jay dumped a single on a two-strike changeup — a pitch the Dodgers knew he has struggled against. Ketel Marte worked a walk next. The big blow followed. Buehler threw a 97-mph fastball over the outer half to David Peralta and he split the right-center field gap for a two-run double to put the Diamondbacks ahead and continue the seesaw battle between the clubs in the Diamondbacks’ eventual 4-3 victory.

“I wouldn’t say it was a mistake,” Buehler said. “It wasn’t that bad of a pitch, but he got the barrel to it and hit where he wanted it so tip my cap to him.”

Buehler completed the inning by striking out Paul Goldschmidt, an MVP candidate, for the third time with his 87th pitch. That’s how his night ended. The right-hander finished with five punchouts. He surrendered four hits and walked two. He didn’t have his typical swing-and-miss stuff. He wasn’t as lights-out as he was in his previous two starts, when he didn’t allow an earned run and compiled 21 strikeouts to three walks in 14 innings, but he worked around that to deliver six strong innings with help from two double plays.


“He was good and did enough to win the baseball game,” Dodgers manager Dave Roberts said.

The 24-year-old Buehler has used the season’s second half to realize his potential and cement his spot in the Dodgers’ rotation behind Clayton Kershaw. He has accumulated a 2.30 ERA in 781/3 innings across 13 starts while entering uncharted workload territory as a professional. If the Dodgers advance to the National League division series, he will likely pitch Game 2. He is vital to their World Series chances.

Meanwhile, run support has been spotty for him during the stretch. The Dodgers have scored three or fewer runs in 10 of those 13 second-half outings. As a result, they’re 7-6 in his starts. The margin for error was thin again Tuesday. The Dodgers claimed an early lead on Cody Bellinger’s leadoff homer in the second inning, but didn’t score again until they tied the game in the seventh. The situation forced Roberts to pinch-hit Chase Utley for Buehler with a runner at first base and no outs. Utley flied out and the Dodgers left two runners on base anyway. They finished two for 12 with runners in scoring position and left nine runners on base as their lead in the NL West dwindled to a half-game with four games to go.

“That’s the way this game goes, especially in the National League, and I understand it,” Buehler said. “I got through six and I was going pretty good through five. ... My mechanics weren’t perfect today. I didn’t execute the way that I really wanted to. Breaking ball wasn’t that sharp, but I threw some two-seamers and got some double-play balls when I needed it to keep my pitch count low to where I could kind of stay in that sixth inning and wear that. That’s the way the game goes.”


jorge.castillo@latimes.com

Twitter: @jorgecastillo