SAN DIEGO -- With the baseball season lasting six months and 162 games, a manager has to take the long view even when every fiber of his competitive being wants to go all out every single night for the win.

Approaching the marathon like a sprint, though, is a good way to burn out your bullpen or get relievers hurt. Those are not things that D-backs skipper Torey Lovullo is going to do.

Over the course of the season, that should pay off. But there will be nights like Friday, when Lovullo had to leave a reliever in longer than he’d like and watched his team fall, 10-3, to the Padres at Petco Park.

The roots of the D-backs’ bullpen situation date back to May 30, the third game of a stretch of 13 games in 13 days. That grind ends Sunday, after the series finale with the Padres.

Zac Gallen started that May 30 game for the D-backs against the Mets at Citi Field. After allowing a leadoff single, he had to be removed from the game with a strained right hamstring. Lovullo had to use six relievers to get through that game.

The next night, Jordan Montgomery went just four innings, and Slade Cecconi followed with a 4 2/3-inning performance. Montgomery also turned in a two-inning stint Wednesday, which again left the bullpen with a lot of innings to cover.

“We’re still showing the effects of the Gallen situation,” Lovullo said.

The D-backs have shuffled some of their relievers over the past week. They called up Humberto Castellanos and Joe Jacques from Triple-A Reno on Thursday to give them some coverage and claimed right-hander Thyago Vieira from the Orioles.

Jacques arrived in San Diego midgame Thursday and went unused because Lovullo went with his leverage pitchers to get a 4-3 win.

When Vieira arrived in San Diego on Thursday, Jacques was sent back to Reno without having thrown a pitch or even watched a full game.

Heading into Brandon Pfaadt’s start Friday, Lovullo’s plan was to only use his leverage relievers if the D-backs had a lead or were within one run. Using them if they were down more than that would only exacerbate the bullpen issues.

Pfaadt wasn’t as sharp as he had been recently, but he kept the deficit to 3-0 through five innings before Ha-Seong Kim hit a two-run homer in the sixth that chased him from the game.

Lovullo planned to have Castellanos pitch the rest of the game to give the rest of the bullpen the night off.

“We were trying to have the bullpen reset today,” Lovullo said. “We've been getting after the guys pretty good, and we asked them to go out there for [2 2/3] innings and haul that workload.”

When the D-backs cut the score to 5-3 in the seventh, Lovullo stuck with Castellanos. Had the D-backs gotten to 5-4, Lovullo would have used other relievers.

Castellanos held the Padres scoreless in the seventh, but San Diego broke the game open with a five-run eighth inning, and Vieira had to come in to get the final out of the inning.

“You can’t throw your top guys all the time,” Lovullo said. “The next thing you know, they’re going to have 75 appearances. And we don’t want to do that.

“So sometimes you have to bite the bullet, and today was one of those days. I knew going in that if we were not [ahead] I wasn’t going to use any of the [leverage] relievers.”