PITTSBURGH -- Before the Pirates beat the Cubs on Thursday afternoon, manager Derek Shelton sat down inside the PNC Park press conference room wearing a blue T-shirt from the Carnegie Science Center that shared a message: “Think like a proton. Stay positive!” That’s easier said than done some days, Shelton admitted, especially when Pittsburgh plays a sloppy game.

The Pirates made their share of mistakes, dealt with a handful of frustrating plays and lost, 4-2, in the first game of Friday’s seven-inning doubleheader against the Reds at PNC Park. Pittsburgh only committed one error, its Major League-leading 36th of the season, but seemingly all of the Bucs’ misplays in the field and missed opportunities at the plate came back to haunt them.

• Box score

It might be easy to overlook the Pirates’ fundamental mistakes, as they’ve lost 25 of their first 36 games. Their individual and collective slumps at the plate are more glaring when looking at their top-line statistics. The number of pitching injuries they’ve endured can’t be ignored. But as Pittsburgh works to establish a new culture under Shelton and general manager Ben Cherington, the team needs to play a cleaner, crisper brand of baseball.

“Some of the mental errors we have, we have to combat. Mental errors come in sometimes because of fundamental thoughts. Some of that has to do with awareness,” Shelton said Thursday. “We have to make sure that our players are aware of what the thought process is or what they had and then what it should be and have those conversations.

“We’re gonna make mistakes. Mistakes happen in every course of the game. We have to make sure that we don’t repeat the same mistakes.”

With a runner on first base and two outs in the second, Curt Casali hit a soft 67.4-mph liner toward first baseman Josh Bell. The ball came with an expected batting average of just .320, according to Statcast, but it bounced off Bell’s glove for an error and the inning continued. The next batter, Jose Garcia, smacked an RBI single to left field to give Cincinnati a 1-0 lead.

After Joey Votto hit a leadoff single to right in the third inning, Nick Castellanos smacked a hard grounder that shortstop Erik González stopped with a diving effort. González, who came up favoring his left side, might have been able to flip the ball to second base to start a double play, but second base was unoccupied as Kevin Newman broke toward the ball due to the way the Pirates were shifted. After a Matt Davidson groundout, Eugenio Suárez drove in Votto with a sacrifice fly to right field.

"It's not mistakes behind me that I care about. If I ever stop walking people or throwing pitches down the middle every now and then, then I'll say something,” Brault said. “Everybody makes mistakes. I don't care about that. It's frustrating to get the weak contact that just happens to go to the right spot over and over and over again. That's more frustrating.”

Jesse Winker then hit a bloop to shallow center field, drawing Cole Tucker in from deep center and González out from shortstop. Both fielders pulled up as the ball dropped, allowing what could have been the third out to land between them for an RBI single.

"If anyone should call it, it's me. I just didn't think I had a beat on it,” Tucker said. “But hindsight [being] 20/20, knowing he got banged up the play before, I probably should've moved in a little bit, if anything. … Playing deep, Winker hitting ... it's perfect -- you know, just a dunked-in, dropped-in ball. It happens."

The misplays and bad batted-ball luck made for a longer-than-necessary day for Brault, whose only real mistake came on a slider left over the plate that Castellanos launched into the bullpen for a leadoff homer in the fifth. Brault struck out six and only walked two but needed 96 pitches to record 14 outs.

"I just threw it right down the middle. The idea was to get low and in, get a roll-over ground ball,” Brault said of Castellanos’ homer. “But he did a good job of staying behind it, and I put it over the middle and he hit it. It happens. It's the big leagues. You make mistakes, sometimes people take advantage."

The Pirates put themselves in position to score against Reds starter Luis Castillo despite his characteristically unhittable changeup and a fastball that topped out at 99.7 mph. They just didn’t capitalize in situations that demanded it.

In the second, Colin Moran singled and Gregory Polanco doubled to put runners on second and third with nobody out. But Bell flied out, Moran ran into an out on Ke’Bryan Hayes’ line drive to third base and Tucker grounded out to end a scoreless inning.

The Bucs broke through in the third, when Moran singled home González and Polanco doubled again to score Bryan Reynolds. Bell struck out to strand two more runners in scoring position, then a two-on, nobody-out rally in the fourth fizzled when Castillo struck out Jacob Stallings and got González to ground into a double play.

"He's obviously a really good pitcher for a reason. The difference between his fastball and changeup is perfect for what he's trying to do,” Tucker said. “But I feel like we did have some good at-bats today. We just didn't piece together what we needed to. We had guys on, we just didn't come through.”