SAN FRANCISCO -- Johnny Cueto isn’t one to make excuses, but a couple of factors seemed to be working against him on Monday night.

He’s been dealing with tightness in his hip that prompted the Giants to push his scheduled start against the A’s on Sunday back one day. His personal catcher, Chadwick Tromp, was a late scratch after tweaking his right shoulder on a dive back to first base on Sunday. The Giants instead started Joey Bart, who struggled to get on the same page with Cueto when they were paired for the first time on Aug. 25.

Either way, Cueto couldn’t seem to find his rhythm in the Giants’ 7-2 series-opening loss to the Rockies at Oracle Park. The 34-year-old right-hander was charged with seven runs over 4 1/3 innings, marking the worst outing of his five-year tenure with the Giants.

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“I'll say that he didn't have his best stuff and his command was off,” manager Gabe Kapler said. “Against a team like the Rockies, who are kind of free swingers up and down the lineup, if you're missing in the zone, they can punish you for that. That's really what was happening with Johnny. He was missing in the zone with all of his pitches and with the lack of his best stuff, he wasn't missing bats today.”

San Francisco’s offense, which entered Monday averaging 5.84 runs per game at Oracle Park this year, faltered, too. The Giants hoped to ride the momentum from their 14-2 rout of the A’s on Sunday into their final homestand of the year, but they cobbled together only five hits against Rockies right-hander Germán Márquez, who surrendered only an RBI single to Donovan Solano over six innings.

Alex Dickerson added a solo shot off reliever Carlos Estévez in the seventh to finish 3-for-4 in his first game since returning from the paternity list. Dickerson missed two games over the weekend to attend the birth of his first son, Levi Ross, but his return ended on a disconcerting note after he was struck on the right elbow by an 89.7 mph slider from Tyler Kinley in his final plate appearance in the ninth.

Dickerson was visibly grimacing on the bases and underwent X-rays following the game, which came back negative. The Giants can ill afford another injured outfielder, as Mike Yastrzemski (calf) and Austin Slater (elbow) are already unavailable to play defense.  

The defeat dropped the Giants (26-27) out of playoff position with only seven games left to play. They slipped one game behind the Reds (28-27) for the first National League Wild Card spot and a half-game behind the Phillies (27-27) for the second, putting pressure on them to bounce back quickly from their sixth loss in their last nine games. 

Cueto has now allowed at least six runs in three of his last five starts, causing his ERA to spike to 5.53 over 11 outings this year.

He induced only one swinging strike on his changeup, which entered Monday with a 35.5 percent whiff percentage this year. His velocity also appeared to be down a tick, as he averaged 90.3 mph on his four-seam fastball, slightly below his season average of 91.4 mph. Cueto began to experience discomfort in his hip during his start in Arizona on Aug. 30, but he said he didn’t feel like the injury was a factor against the Rockies. 

“I think it was mainly just a couple of pitches I left in the middle,” Cueto said. “I don’t think it’s a big deal. I just have to keep working. I’m hoping that we can qualify for the playoffs.”

The Rockies jumped out to a 2-0 lead in the first inning on back-to-back, two-out RBI singles by Josh Fuentes and Ryan McMahon. They extended their lead on former Giant Kevin Pillar’s solo homer off Cueto in the third and cashed in another run after Sam Hilliard doubled and scored on a balk in the fourth.

The balk came on one of Cueto’s signature shimmies, a sign that it just wasn’t his night.

“I was surprised a little bit,” Cueto said. “I know I did not come to a complete stop, but I moved my shoulders. That’s what it is.”

Cueto faced more trouble in the fifth after the Rockies loaded the bases with one out on a pair of walks and a single. He got ahead of Elías Díaz, 0-2, and thought he had strike three on a sinker at the bottom of the zone, but the pitch was called a ball by home-plate umpire Ted Barrett.

Three pitches later, Díaz lined a curveball to left field for a two-run single that made it 6-0 and knocked Cueto out of the game. Reliever Wandy Peralta came in to replace Cueto and allowed an inherited runner to score on an RBI single by Garrett Hampson.

Despite the poor results, Cueto and Bart seemed to have an easier time working together. Tromp had trouble getting his shoulder loose before the game, but he was deemed healthy enough to catch the final inning of the game after Kapler opted to pinch-hit for Bart with two on in the eighth.

“We were fine,” Cueto said. “There’s no reason to blame anybody. We’re going to get to know each other. We’ve just got to continue working. The more we work together, the better we’re going to get.”

Cueto’s slide comes at an inopportune time for the Giants, who will need better production from their starting rotation if they are to keep their playoff hopes alive down the stretch. Cueto will likely have at least one more opportunity to get back on track, as he’s lined up to start the penultimate game of the regular season against the Padres on Saturday.