SAN DIEGO -- Marlins left-hander Caleb Smith threw 93 pitches Friday night at Petco Park. It was his misfortune that they turned out to be 93 high-stress pitches.

With the Marlins unable to muster much offensively against Padres lefty Joey Lucchesi, Smith’s bounce-back start went for naught in a 5-2 loss to open a six-game road trip.

The focus might have been on Smith’s eight strikeouts in five innings, or it might have been on how he regained his command after allowing five runs and eight baserunners in only three innings last time out vs. the Nationals. Instead, the focus went to two of those 93 pitches.

• Box score

The first was a 2-2 slider in the first inning that Franmil Reyes lined into the left-field seats with an 111.7 mph exit velocity. The second was a 2-2 changeup in the fourth inning that Hunter Renfroe deposited into the second level of seats in front of the Western Metal Supply Co. Building.

“I thought he threw the ball really well,” manager Don Mattingly said. “We saw some of the things we’ve talked about before -- more swing and miss, which is his signature.”

While Smith was in the game, the Marlins got only one hit off Lucchesi, a double to the center-field wall by Miguel Rojas in the third. Miami trailed 2-0 when Smith’s spot came up in the top of the sixth and his pinch count was creeping up, so Mattingly opted for an offensive spark and called on Rosell Herrera to pinch-hit.

That move worked to perfection as Herrera responded with his second career pinch-hit homer to close the gap to 2-1, but it also got Smith out of the game. The Padres tacked on two runs in the seventh inning and another one in the eighth to put the game, for all intents and purposes, out of reach.

The Marlins finished the month of May with 17 home runs and 89 runs scored, ranking last in the Majors in each category. That follows an April in which they ranked last with 18 homers and 68 runs.

With no room for error Friday, Smith was left to pick apart where he fell short of perfection. He said Franmil hit “a decent slider,” but the changeup to Renfroe was over the plate. And though his overall feel was far superior than the outing vs. the Nats, Smith was not satisfied with his fastball command.

“Fastball away was good; fastball in, not so much,” he said.

Still, the outing has to be considered a return to the norm for Smith. He allowed only three hits and two walks. He ranks eighth in the National League with a 3.10 ERA and he has allowed two or fewer earned runs in nine of his 11 starts.

There wasn’t anything mechanical to work on in the bullpen between starts after the last outing, Smith said. It was just about getting that feel back. And that was accomplished.

“Being able to throw my slider backdoor for strikes -- that was huge for me,” Smith said. “Getting strike one early. Being able to throw my offspeed [pitches] for strikes -- that really helped out.”

Alfaro exits with jaw soreness

Marlins catcher Jorge Alfaro took a hard foul tip off the bat of Ian Kinsler in the seventh inning and left the game the following inning because of jaw discomfort.

“I don’t know how sore it’s going to be tomorrow,” Mattingly said. “But it didn’t sound like they’re talking about the concussion protocol. I think that was good news. The doctor was just in there, and they didn’t see any signs of that.”

Alfaro has started 41 of the Marlins’ 55 games. Backup catcher Chad Wallach is sidelined by a concussion, and Bryan Holaday has taken the backup duties.

Notable

• Harold Ramirez saw his 10-game hitting streak end as he went 0-for-3 with a walk. He is the second Marlins player to put together a 10-game streak in his first 20 Major League games. Christian Yelich did it in 2013.

• Herrera has three career homers, the last two as a pinch-hitter. He had a pinch-homer on May 28 against the Giants’ Sam Coonrod.

“He’s been good off the bench, really good,” Mattingly said. “It’s been good to see. Might have to think about getting him in there.”