By Jon Weisman

The question with Hyun-Jin Ryu tonight, or at least one of the big ones after he spent more than a year recovering from shoulder surgery, was about the effectiveness of his fastball.

The San Diego Padres didn’t have much trouble answering it, knocking eight hits and scoring six runs over 4 2/3 innings, the length of Ryu’s first big-league appearance since the 2014 playoffs, in a 6-0 victory.

Ryu struck out four — two on curveballs in the 70s, one recorded as an 85 mph slider and one as an 81 mph changeup. But he otherwise struggled to put away hitters, from the 2-2 first-inning homer he allowed to leadoff hitter Melvin Upton Jr. (the first leadoff homer ever hit against Ryu as a Dodger) to the 1-2 RBI single he allowed in the second inning to opposing pitcher Drew Pomeranz, who also threw seven shutout innings.

The 29-year-old Ryu pitched a perfect third inning, but gave up a run in the fourth and couldn’t get the third out in the fifth, succumbing to back-to-back doubles by Matt Kemp and Yangervis Solarte, followed by a 108 mph Alex Dickerson triple whose flight, admittedly, Yasiel Puig misread in right field. (Casey Fien relieved Ryu and recorded the final out of the fifth.)

Meanwhile, with much less publicity, there was another return engagement tonight. In the fifth inning, Carlos Frias entered a Major League game for the first time in nearly 10 months, and acquitted himself well, finishing off the final four innings and providing the rest of the bullpen a much-needed respite.

Frias had to escape a bases-loaded eighth inning and two mean-looking fly balls to the right-center wall in the ninth, but became the first Dodger since Travis Schlichting in 2010 to pitch four innings of shutout relief — and needed only 52 pitches to do it. Three of his four innings were one-two-three.

The Dodger offense managed four walks and two hits, none of them by Corey Seager, whose hitting streak ended at 19. Still standing: Tommy Davis’ 56-year-old L.A. rookie hitting streak record (20 games) and Jackie Robinson’s franchise mark (21).