PITTSBURGH -- In his Reds debut on Thursday vs. the Pirates, starting pitcher Luke Weaver got settled in and began commanding his pitches better during the second inning. It proved one inning too late. 

Pittsburgh scored four runs in the bottom of the first inning on back-to-back home runs, as Cincinnati was handed its third straight defeat during a 4-3 loss at PNC Park.

"First one out there, it’s kind of tough to gauge the emotion and kind of feel like you’re grounded and able to attack," Weaver said. "It was coming out real good, but just felt like I was just missing down or in or out. Once I got past the nitpicking and just started going after them, I felt like the stuff started to play better.”

Weaver, who missed the first three weeks of the season with a right elbow flexor strain, gave up four runs and four hits over six innings, with two walks and eight strikeouts.

The performance was one of the better ones of late from a Reds rotation that has struggled to put up zeroes. Over the past seven games -- including five losses -- their starters have posted a 10.62 ERA. That stretch includes Graham Ashcraft throwing seven scoreless innings in Saturday's 13-0 win vs. the Phillies and Hunter Greene's injury-shortened three scoreless against the Rays during an 8-1 win on Monday.

Starters falling behind quickly has been critical in each of Cincinnati's losses. Thursday marked the third time in the past five games a Reds starter opened a game giving up four or more runs in the first inning.

There were two on and two outs when Weaver was one strike from escaping the first inning scoreless. In a six-pitch sequence against Connor Joe, the right-hander threw five fastballs. The last one -- in a 3-2 count -- was left over the middle and it got crushed for a three-run homer to center field.

“That one is going to be tough to sleep on," Weaver said. "Hitters, when you throw repeated pitches, they get the timing going. I felt like I had to make a perfect pitch in the 3-2 [count] in a big moment. I just overdid it. It just ran back."

In the next at-bat, Jack Suwinski hit a 2-1 fastball to right field for a homer that made it a 4-0 game. Weaver and the bullpen duo of Alex Young and Buck Farmer combined to pitch seven scoreless with one hit allowed the rest of the way.

"Luke was really good today," manager David Bell said. "Good fastball. Used all his pitches. Especially after the first inning, he started mixing his pitches well. You give up four runs in the first and part of it is he’s a good pitcher. Part of it is he wanted to do everything he could to keep us in the game and give us a shot to win. That’s exactly what he did."

The key to Weaver's turnaround was his changeup. Of his 93 pitches, 33 were the changeup, according to Statcast.

"Watching from the side, it had a lot of action, a lot of depth and he threw the ball well," Pirates manager Derek Shelton said.

Weaver's changeup got 12 swings and seven whiffs, as it accounted for seven of his eight strikeouts.

"I was just a little soft and guys started taking it. They weren’t chasing it the way I would hope they would. I felt like I was kind of guiding it a little bit," Weaver explained. "Then I realized, ‘OK, let’s use some more arm speed, kind of get fastball intensity,’ and then the swings started to come. I was able to throw it in the zone and get some in-zone swings."

Cincinnati's recent struggles haven't all been on starting pitching. The Reds have been outscored by 19 runs (22-3) in the past three games. After 24 consecutive scoreless innings, including six against Pirates starter Roansy Contrereas, the fever broke in the seventh when Jason Vosler lofted a two-out blooped single to center field. The Reds scored two more runs in the eighth inning, including Jonathan India's RBI single for his third hit of the game.

Weaver -- who signed a one-year, $2 million contract in January -- still came away encouraged by his outing and thinks it could build momentum into his next start.

"Length through a start, especially early when you’re kind of down a little bit mentally, physically, on the scoreboard," Weaver said. "That’s the job -- to get length and not hurt the bullpen and to give us a chance to win. Just a tad short today.”