PHILADELPHIA -- When starting pitcher Justin Dunn arrived in a Spring Training trade that sent Jesse Winker and Eugenio Suárez to the Mariners, the Reds knew he was still recovering from a right shoulder injury suffered in June 2021. Dunn did rehabilitation and got into the rotation in early August, but he is now finally showing what he can do when healthy.

It was a strong showing for Dunn on Thursday, yet it wasn't enough for the Reds to avoid a four-game series sweep to the Phillies during a 4-0 loss at Citizens Bank Park, as opposing starter Aaron Nola delivered a complete-game five-hit shutout with 11 strikeouts.

Dunn did his part, as he tied a career high by pitching six innings, giving up just two earned runs on four hits and two walks. He struck out five while throwing 92 pitches.

“That’s a quality start. Against this team, he showed what he is capable of," Reds manager David Bell said.

Four starts into his return to the big leagues, Dunn has appeared to have found his footing, especially over his past two starts. On Saturday at Pittsburgh, he allowed one earned run -- on a solo homer -- on three hits and four walks over five innings during a 10-1 win.

"I got back to work this week, fell back on my routine," Dunn said. "Worked on some stuff with [pitching coach and director of pitching Derek Johnson], a couple of mechanical things. I just got out of my way out there. Going into a game against Nola, you know it’s going to be tight on runs, right? I had to do my job to be efficient."

Philadelphia's hitters were mostly limited to soft contact by Dunn, save for one booming homer by Kyle Schwarber. With two outs in the third inning of a scoreless game, Schwarber crushed a 1-1 changeup and knocked the top of the batter's eye in center field with a Statcast-projected distance of 451 feet.

"Missed execution there. It was pretty impressive what he did with it. I’ve never seen a ball get hit like that, especially a changeup," Dunn said. "The ball has to be a hair more down or a hair off the plate. That’s something [catcher Austin Romine] has been talking to me about, of guarding misses. I’ve got to do a better job of guarding that miss and getting the ball where I need to get it to, so we can get another pitch to execute later."

While the little-used changeup was thrown only four times, Dunn had better success using his breaking pitches. His slider notched six misses on 14 swings, while the curveball got five whiffs on 12 swings.

The second batter of his night, Rhys Hoskins, missed badly chasing an 83.4 mph slider that dove low and away.

"I spin the ball. That’s what I do," Dunn said. "That’s what I’ve done my entire life. I learned a curveball at 10 years old, so that pitch right there, I can tell from the first pitch in the bullpen if I have it or not."

In the fifth inning, Garrett Stubbs led off with a bunt single to third base on which Nick Senzel possibly hurt his hamstring trying to retrieve the roller. Senzel continued in the game, and Dunn followed with a strikeout, but Bradley Zimmer added a single that set up the game's second run on Edmundo Sosa's sacrifice fly.

Dunn pushed through in the sixth inning, allowing only a one-out walk. It was his first six-inning start since Sept. 6, 2020, for Seattle.

"Coming into the game, I wanted to go deep for those guys out there. They’ve been grinding, and I set my intentions on trying to go six or seven and giving [the bullpen] the least amount of workload as possible," Dunn said. "To be able to do that and execute at a pretty high rate tonight, I’m very happy with where I was."

Good news has been in short supply lately for the Reds' rotation. It is missing injured rookies Hunter Greene (shoulder) and Graham Ashcraft, who went on the injured list Tuesday (retroactive to Saturday) with right biceps soreness. The pitcher who replaced Ashcraft -- T.J. Zeuch -- pitched 2 2/3 innings and allowed six runs on seven hits and four walks in a start Wednesday, then was placed on the IL with back soreness earlier Thursday.

Reliever Luis Cessa was moved into the rotation but isn't stretched out. Cessa threw two innings during Monday's loss. That made Dunn's outing even more welcomed.

"Clearly, he’s healthy. When he came out of the game, he was pretty fired up," Bell said. "He felt like he’s back now. It was a really good start.”