PHOENIX — As another quiet day from his well-accomplished lineup drew to a close, Dave Roberts had to try something. Nothing has been working for the Los Angeles Dodgers as of late, so Roberts sent Max Muncy out to the on-deck circle to pinch hit for Teoscar Hernández with two outs in the ninth inning, searching for a spark.Hernández is here for his bat. But the quality of his recent at-bats warranted a change. Hernández is not blameless in the Dodgers’ offensive morass, but there is plenty of blame to go around.Muncy struck out on four pitches to end a 4-2 loss to the Arizona Diamondbacks, and with it closed the book on a forgettable trip in the midst of their worst stretch of the season. The silence that hung in the batter’s box and the postgame clubhouse did not reek of desperation or frustration, but it felt familiar.How Tarik Skubal strengthens the Dodgers' repeat bidKatie Woo and Jeshua Kidd“There’s certainly not panic,” Roberts said. “I think for us, it’s just finding a way to win, win a game, and win consistently.”That has been hard to come by. The Dodgers have now dropped eight of their last nine games and 15 of their last 24. They have played like a middling club for the better part of the month. Baseball’s presumptive juggernaut is showing cracks.“There’s no concern in here,” Freddie Freeman said. “We’re a good team.”Their All-Star breakout starter continues to slide, as Justin Wrobleski could not get a fastball far enough in to Ketel Marte, and the Diamondbacks slugger clobbered it for a two-run homer. Wrobleski did not help his case an inning later when he fielded a bunt and fired it too high and wide for Tommy Edman to stay on the base, leading to more damage. Wrobleski, whose value in the first half came from his ability to soak up innings, managed to record just 10 outs and exited with a 4-0 deficit.This is all still new for Wrobleski, who in his first full season as a starter has learned the difficulty of surviving the monthslong grind. He has allowed nine home runs over his last three starts. He’s allowed 17 runs in 20 innings since the All-Star break.“I’m just not good enough right now,” Wrobleski said. “It’s kind of what it comes down to. It’s really frustrating. Execution just hasn’t been as good. I feel like today just wasn’t good enough. And, again, I gotta be better.”Even with their early deficit, the game remained in reach if the Dodgers offense could muster much of a pulse. Eduardo Rodriguez, a surprise All-Star, became the latest Arizona starter to chew up outs against them with ease. Torey Lovullo, the Diamondbacks manager, did not move from his post as Shohei Ohtani stepped up to the plate for the fourth time, with Rodriguez’s pitch count up to 111. Ohtani grounded out four pitches later, keeping the Dodgers down 4-2 as Rodriguez finished his seventh inning of work. Rodriguez, Brandon Pfaadt and Merrill Kelly combined to allow just three runs over 19 2/3 innings this weekend.The offense is an area of growing concern. It entered Sunday ranking 23rd in baseball with a 93 wRC+ since the start of July. Those numbers are even worse this month (88 wRC+). It is reminiscent of the offensive skid it ran into last July, when it ranked as a bottom-five offense in the sport and sparked a similar level of pearl-clutching over the lineup’s collective age. The game’s oldest position player group has been waiting for its stars to carry them all season.It is August, and Mookie Betts has a .674 OPS. Kyle Tucker, who added an RBI triple Sunday and has quietly had a good trip, still is staring at a .727 OPS. Hernández has a .717 OPS and has not looked like the lefty masher he was two years ago; Rodriguez, a lefty, blew three straight fastballs past him in the sixth inning with Hernández representing the tying run. Muncy, the metronome for this offense, has endured his worst month of the season (.594 OPS entering Sunday). The benefit of having stars is they are supposed to help a team establish a floor. That floor has bottomed out during this stretch.Opposing pitching staffs have appeared to find a hole. Since July 1, no team in baseball has seen a higher percentage of fastballs than the Dodgers have (58.7 percent). The Dodgers have produced a .693 OPS against those pitches in that span, including the fourth-worst on-base percentage (.310) and fifth-worst slugging percentage (.383) in those spots.“I think this series it was very clear that we weren’t hitting the fastball and we were exposing ourselves to the changeup with the secondary specifically,” Roberts said.Fixing that does not fix everything for this lineup.“We have to make adjustments,” Roberts said. “I think for me that’s sort of what I see as a group — we’re just not making adjustments.”This stretch has endured long enough to raise some questions about the integrity of a lineup that, on paper, didn’t have many holes. A solid week could wipe them all away. Baseball is funny that way. The Dodgers, of course, still have a strong grasp on first place even after dropping the season series to the second-place Diamondbacks. They still possess as much talent as any team in the sport. Their rotation early next week starts with a pair of two-time Cy Young winners, Tarik Skubal and Blake Snell.It would help ease those lineup concerns if the Dodgers started playing like the team they were billed to be.“We’re certainly not playing up to our capabilities,” Roberts said. Maybe that starts Monday, back at Dodger Stadium against Kansas City.