SAN FRANCISCO — Trevor McDonald wasn’t the headliner of the Giants’ roster shakeup Monday, but credit the third-billed newcomer of the day with making the moves look good.

Neither top prospect Bryce Eldridge nor hot-hitting rookie Jesus Rodriguez gave the Giants’ offense the jumpstart it needed. But McDonald was brilliant beyond expectations.

The 25-year-old right-hander, called up to make a spot start, held the Padres to one run on two hits over seven innings in a 3-2 win to open a six-game home stand. The club was in desperate need of a course correction after going winless on its six-game road trip.

Eldridge, the Giants’ No. 1 prospect, went hitless in two at-bats with a walk in his return to the majors after a brief 10-game stint last September. Rodriguez, who sported a .330 average at Triple-A, put his funky stance on display in the bigs for the first time but came up empty in three at-bats.

Instead, it was an increasingly common character who got the Giants on the board: Casey Schmitt, who launched a solo home run off Padres starter Randy Vasquez in the first inning.

The solo shot was the Giants’ first home run since they left home last Sunday, ending a six-game drought. It was their 20th as a team, still the fewest in the majors, and Schmitt’s fifth, leaving the Mets as the only team without a player to hit at least five.

Caleb Killian recorded the final three outs to earn his first career save, but not without drama. He served up a 447-foot homer to the first batter of the inning, Ramón Laureano, before getting Fernando Tatis Jr., Jackson Merrill and Manny Machado in order to preserve the one-run lead.

What it means

San Francisco snapped a six-game losing streak dating back to the start of its last road trip.

The Giants improved to 11-3 when hitting a home run; they’re 3-18 when held in the ballpark.

Who’s hot 

Rafael Devers drove in the Giants’ other two runs, only the second time this season the slumping slugger has recorded more than one RBI in a game — his first since April 8. Luis Arraez doubled twice and was driven home by Devers both times, on a single in the first to put the Giants up 2-1 after Schmitt’s homer, and again with a sac fly in the sixth.

Devers has hit safely his past five games — matching his longest streak of the season — raising his OPS to .572 from a low-water mark of .530 last Sunday.

McDonald didn’t allow a hit to anybody besides Merrill, who got him twice, including a solo shot to straightaway center that briefly put the Padres ahead 1-0 in the top of the first.

Since two relief outings to begin his big-league career, McDonald has made three starts totaling 20 innings while surrendering just two runs — a 0.90 ERA. He has a 21:1 strikeout-to-walk ratio in his three starts after racking up eight more Ks without issuing a walk against San Diego.

Schmitt is responsible for the last three home runs hit by the Giants, dating back to last Saturday, hitting safely in nine of his past 10 games. Over the stretch, dating back to the start of their series against the Marlins, Schmitt is 13-for-36 (.361), raising his average to .308 and OPS to .901.

Who’s not 

It was largely the same story for the rest of the Giants’ lineup, which was held to three runs or fewer for the 23rd time in 35 games this season — three more than any other team.

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With the chance to add on with runners at the corners and two outs in the eighth, Willy Adames struck out swinging, the second time he offered at a pitch above the strike zone for strike three.

Up next

The Giants will look to make it two in a row Tuesday against RHP Walker Buehler, who they beat 3-2 in the second series of the season. They’ll have their ace, Logan Webb, on the mound.