PITTSBURGH — Reynaldo López and Chris Sale have been two of baseball’s biggest surprises this year. But has their success been more surprising than the prolonged struggles of a lineup that is essentially the same one which was compared to the 1927 Yankees last year?

With their 4-1 loss to the Pirates on Saturday afternoon at PNC Park, the Braves scored one run or fewer for the seventh time through 49 games this season and for the fourth time in their past 11 games. They scored fewer than two runs an MLB-best 12 games all of last year.

“It’s a long season, and we still know we can turn it around at some point,” Braves center fielder Michael Harris II said. “We’re just going to keep doing what we’re doing and try to correct some of the little things.”

A couple of significant changes may come on Monday, when veteran catcher Sean Murphy and third baseman Austin Riley could return to the lineup. Murphy has been out since he strained his left oblique on Opening Day. Riley has been sidelined since he exited a May 12 game against the Mets with tightness in his left side.

The Braves have scored one run or fewer in four of the 13 games Riley has missed.

“I think that will be a big shot for all of us,” Braves manager Brian Snitker said. “It will just lengthen our lineup again.”

With a 26-man roster and the universal designated hitter in place, the Braves haven’t felt the need to add a player to account for Riley’s absence. The problem isn’t that they have played short. The problem is they have had to play Zack Short, who is certainly not Riley.

This was the roughest start of the year for López, who wasn’t at his best as he allowed three runs (two earned) and five hits before a rain delay ended his day with two outs in the fifth inning. But one can’t ask for much more from a pitcher who has posted a 1.75 ERA through his first nine starts. A lack of consistent offensive support has netted him just two wins during this impressive stretch.

“I know everything is going to change,” López said. “I believe in my guys here.”

Nobody is overly concerned about how many wins López tallies this year. But it’s hard to explain how the Braves’ offense hasn’t got on track this year. This is pretty much the same lineup that matched an MLB record with 307 homers last year. They also had a .501 slugging percentage, becoming the first AL/NL team to ever slug .500 or better. Jarred Kelenic replacing Eddie Rosario accounted for the only offseason lineup change.

So why are the Braves slugging just .407 through this season’s first 49 games? Slugging .500 a second straight year might have been a tad optimistic. But seeing this powerful bunch get outslugged by the Royals (.412) thus far was also likely not on many bingo cards.

Everything started with Ronald Acuña Jr. during his historic 40-70 season last year. The reigning NL MVP has hit .246 with four homers and a .704 OPS this year. His expected statistics indicate he has been the victim of some tough luck. His .260 expected batting average trumps his real batting average, and his .414 expected slugging percentage trumps his .356 real slugging percentage.

But Acuña is far from the level of production he provided last season, when he hit 41 homers, slugged .596 and had a 1.012 OPS.

The same could be said of Matt Olson, who is coming off a season in which he slugged .604 and hit a franchise-record 54 homers. He has tallied seven homers and slugged .396 thus far.

Olson’s expected numbers actually indicate the law of averages will help him more than Acuña. Olson’s .220 batting average is trumped by his .255 expected batting average and his slugging percentage is easily trumped by his .482 expected slugging percentage.

“I’ve always said hitting is contagious,” Olson said. “It was contagious when we were all squaring balls up last year. Sometimes, it can be contagious the other way, too. You just need a couple of balls barrelled back to back and you have a big inning, and there we go.”