SAN FRANCISCO -- Johnny Cueto made his first rehab start with the Arizona League Giants on Sunday, striking out five over two scoreless innings in a dominant 21-pitch outing. The encouraging performance, Cueto’s first since undergoing Tommy John surgery last summer, is the latest indication that the 33-year-old veteran should be ready to help the Giants in September. 

Until then, the Giants will attempt to patch together the fifth spot in their rotation, which has remained in flux since Drew Pomeranz (now with the Brewers) was demoted to the bullpen two weeks ago. Pitching prospect Conner Menez was called up Tuesday to get his second look with the Giants, but he delivered an uneven showing in a 5-3 loss to the Nationals at Oracle Park.

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Menez gave up five runs, including a pair of home runs to Kurt Suzuki and Trea Turner, over six innings as the Giants (56-58) lost for the eighth time in their last 12 games, sealing their third consecutive series defeat. The skid comes at a critical juncture for the Giants, whose next four games are against the Nationals and Phillies, two teams they’re chasing in the National League Wild Card race.

Menez made his MLB debut on July 21 and allowed two runs over five innings against the Mets, but he was less effective in his second Major League start. He issued two walks in the first inning, one of which came around to score on an RBI single by Suzuki. Menez surrendered three more runs in the third, capped by Suzuki’s two-out, two-run homer that made it 4-0. Turner added a solo shot in the fifth.

“My fastball was kind of there, kind of off sometimes today,” Menez said. “I thought I got squeezed just a bit today. I’m just trying to adjust to tighter zones a little bit here. The positive was definitely going six innings. I was really happy to at least go six innings for the guys and kind of save the bullpen a little bit. Overall for me, it’s definitely a great experience to be up here and get more innings under my belt.”

With an offense that has come back down to the Earth after a torrid July, the club’s pitching staff is suddenly finding itself operating without much margin for error. The Giants have scored fewer than three runs in seven of their last 12 games, batting just .194 (18-for-93) with runners in scoring position over that stretch.

“You’re going to have these little ruts where you’re not quite putting up the runs like we have been the last five, six weeks,” manager Bruce Bochy said. “It’s going to come down to us pitching a good ballgame and just finding a way to win a close one.”

While Madison Bumgarner and Jeff Samardzija have anchored the top of the rotation, the Giants have less stability at the back end, where they are leaning on inexperienced arms like Tyler Beede, Shaun Anderson, Dereck Rodriguez and Menez. The latter two have made spot starts to help fill the vacancy left by Pomeranz, but they’ve combined to post a 7.07 ERA over three outings thus far.

The Giants will need better production from their rotation to stay afloat in the crowded NL Wild Card race, but they’re short on upper-level pitching depth after missing a chance to add another starter at the Trade Deadline. It’s unclear who will get the nod the next time the fifth spot in the rotation comes around, but Andrew Suarez and Logan Webb also remain candidates to start games for the Giants down the stretch.