Dodgers lose lead in NL West after a 7-2 defeat to Diamondbacks

Scott Alexander unleashed a yell the instant A.J. Pollock connected with his sinker, one he immediately wanted back, as he whipped around to watch where Pollock’s drive would land at Chase Field on Wednesday night.

The ball sailed and sailed, the Dodgers’ quandary intensifying the farther it went. The ball settled 422 feet away, over the 25-foot wall in center field, for a three-run home run in the fifth inning. It was the decisive blow in the Arizona Diamondbacks’ 7-2 win, and perhaps, come next week, to the Dodgers’ season.

A few hundred miles north, the streaking Colorado Rockies had continued their drubbing of the Philadelphia Phillies with a 14-0 victory. The combination left the Dodgers (88-71) a half-game behind the Rockies for first place in the National League West.

The Dodgers have three games against the San Francisco Giants remaining in the regular season. The Rockies have four games left —– one against the Phillies on Thursday and three against Washington this weekend, all at home.

In the race for the second wild-card spot, the Dodgers hold a game lead on the St. Louis Cardinals. The list of possible scenarios is endless.

“As far as getting to the postseason, it takes us, we control our own fate,” Dodgers manager Dave Roberts said. “We got to win baseball games.”

Ross Stripling’s inability to escape the second inning Wednesday — he surrendered three runs in 12/3 innings — forced the Dodgers to secure at least 19 outs from their relief corps. After cycling through Pedro Baez and Josh Fields, Roberts was resolute in having Alexander procure all three in the fifth with the Diamondbacks leading 3-2.

Pitching for the third consecutive day, Alexander hadn’t faced a right-handed batter since Sept. 11. His previous six outings were limited to one batter. Each batter was left-handed. Alexander had essentially become a lefty specialist, something Roberts said was the result of the Dodgers’ expanded roster. Before Wednesday’s game, the manager said he trusted Alexander to retire right-handed hitters, but, he reasoned, a crowded bullpen afforded him better options in September.

Alexander was tasked the responsibility twice Wednesday. Paul Goldschmidt was his first right-handed challenge. With a runner on first, Goldschmidt’s hard grounder went off third baseman Justin Turner’s glove for an infield single that bruised Turner’s left thumb. Turner underwent an X-ray after the game and said it came back negative.

Alexander then struck out Socrates Brito, bringing up Pollock with runners on first and second. Roberts stuck with the lefty against Pollock. Three pitches into the at-bat, Alexander served Pollock a belt-high sinker over the plate. He knew it was a mistake instantaneously.

“He’s been in those situations,” Roberts said. “He has the ability to put the ball on the ground. I thought he was throwing the ball well. It just didn’t work out.”

The Dodgers had their chances. They put a runner on base in the first five innings against former Dodger Zack Greinke. But they couldn’t get the big hit, continuing a theme that has plagued the club this season, and Greinke limited Los Angeles to two runs over six innings.

“We got his pitch count up,” Roberts said. “I thought we did a good job against him. Unfortunately, couldn’t put any runs together after that.”

Greinke retired the game’s first two hitters before surrendering hard-hit singles to Max Muncy, Manny Machado and Cody Bellinger. Bellinger’s line drive scored Muncy from third base.

Los Angeles doubled the lead in the second inning. Yasmani Grandal smacked a leadoff double. Stripling then lined a single to center and Grandal’s slide just beat catcher Jeff Mathis’ tag. The Dodgers had a 2-0 lead, one they could’ve expanded, but Joc Pederson grounded into an inning-ending double play on a 3-0 pitch.

The margin instantly evaporated in the third inning. It began with Brito launching a changeup over the right-field wall. Pollock then hit a line drive over Pederson’s head in left field and off the wall. Pederson misplayed the carom, giving Pollock time to race around for his ninth triple. Nick Ahmed drove him in with a double to the right-center field gap. Greinke’s one-out single up the middle gave Arizona the lead and a cycle for the inning.

Stripling didn’t last much longer. Marte followed Greinke with another single, which prompted a mound visit from pitching coach Rick Honeycutt. Eduardo Escobar lined out to right field for the second out, but Stripling walked David Peralta to load the bases. Goldschmidt loomed. Roberts decided he didn’t want Stripling to face Goldschmidt. Roberts pulled him after getting five outs with 47 pitches. It was Stripling’s shortest start of the season.

“I just wasn’t fooling anyone today,” Stripling said.

Roberts summoned Pedro Baez, one of the few pitchers in baseball with an extensive history of success against Goldschmidt. Baez jogged in for the clash having held the perennial All-Star to one hit and three walks in 23 encounters. Baez had struck him out eight times. He added a ninth by blowing a 96-mph fastball past Goldschmidt. Baez released a fist pump after dousing the fire.

The Dodgers threatened again in the third. Turner and Muncy singled. Machado’s fly ball advanced both runners, and Bellinger was intentionally walked with first base open to load the bases. But Yasiel Puig crushed a 100-mph line drive right to the shortstop, and Grandal hit a hard grounder, but into the shift, for the third out.

“Kind of changed the game right there,” Roberts said. “We had him on the ropes a little bit and then he settled in after that.”

The contact was loud, the disappointment was louder. It grew loudest at Alexander’s expense.

jorge.castillo@latimes.com

Twitter: @jorgecastillo