SAN DIEGO -- It was an ideal scenario for the A’s: Closer Mason Miller rested. Setup man Lucas Erceg back from the injured list. A late lead.

Ideal scenarios don’t automatically bring ideal outcomes.

Erceg and Miller each yielded a late home run, and the A’s departed Petco Park on Wednesday afternoon with a 5-4 defeat against the Padres, their fifth straight loss. The last two came on walk-off homers.

“Those two kids at the back end of our bullpen have done a great job this year,” A’s manager Mark Kotsay said. “Obviously, we had a lot of confidence in them to finish out that game. We had it where we wanted it, but we just couldn’t finish it off.

“This Padres team has played really well. They’re swinging the bats well. They’ve got some momentum now, and we were a victim of that in this series.”

The A’s took a 3-2 lead in the sixth inning thanks to some small ball and hustle on the basepaths. They strung together five straight hits for the first time this season during a three-run rally. The five straight hits -- all singles -- were uncharacteristic for an A’s offense that is highly reliant on home runs. (Oakland ranked fifth in the Majors with 79 homers entering Wednesday but was 29th with 3.57 runs per game.)

With the game tied, 2-2, and runners on first and second, Kotsay called for a bunt with left-handed-hitting Seth Brown at the plate against lefty Wandy Peralta. Brown pushed it to the perfect spot on the left side of the infield. It got past Peralta as third baseman Donovan Solano retreated to cover the bag. Shortstop Ha-Seong Kim, meanwhile, began the play positioned up the middle, so he went to cover second base, leaving the left side of the infield dirt vacated.

Tyler Soderstrom, running from second base, noticed and didn’t stop at third base. He broke for home as Kim scrambled to get to the ball. Soderstrom scored standing up to give the A’s the lead.

“Great inning,” Kotsay said. “We played a little bit of small ball. Those are the signs that are encouraging. We swung the bats better this series. There’s some momentum offensively. To see an inning like that offensively, that we can string some hits together, play some fundamental baseball and take a lead there, that’s the right direction for us.”

It certainly seemed the right direction, too, when Erceg jogged in from the bullpen with one out in the bottom of the eighth inning to face the heart of the Padres’ order. It was his first appearance since May 25, as he missed time because of a right forearm strain.

Fernando Tatis Jr. worked a walk before Manny Machado struck out on four pitches. That brought up Solano, who homered off starter Hogan Harris earlier in the game. Solano tied the game by homering to center on a 98.7 mph fastball on the inside part of the plate. It was the hardest pitch hit for a homer against Erceg, and the hardest pitch Solano has hit for a homer.

The walk-off came from rookie Jackson Merrill off a slider from Miller in the ninth.

“One bad pitch and your outing looks like what it is,” Erceg said. “But at the end of the day, it was my first time being back from the IL stint. I felt healthy, and I was happy to be back out there.”

Erceg is eager to get back on the mound in another high-leverage situation. The A’s, as a whole, are equally motivated to erase a painful series. Losses don’t come any tougher than a walk-off, but the A’s have developed thick skins. Twelve of their past 14 losses have been tight games, decided by three or fewer runs.

“It’s baseball,” Harris said. “It’s a game with a lot of momentum one way or another, and it can shift fast. The fact we continue to be right there in games means we’re just this much away. I do feel with the guys we’ve got on this team, it will start turning that way.”