With dirt caked across the front of his uniform, Reds outfielder Nick Castellanos trotted around the bases at Great American Ball Park, his gold chain bouncing with each step. He had just launched a game-swinging grand slam on Wednesday night, tormenting the Cubs' embattled bullpen.

Castellanos performed similar heroics last summer, when he became a cult hero among Cubs fans. In Chicago's 12-7 loss to the Reds on Wednesday, he looked right at home in the role of villain.

• Box score

"He's starting off really good," Cubs third baseman Kris Bryant said. "It's always tough to see someone that you had on your team doing damage against you."

• Cubs turn triple play ... or did they?

The Cubs' offense rallied for seven runs over the final three frames to at least make things interesting, but Castellanos' fifth-inning slam off lefty Rex Brothers sent Chicago on its way to the loss column. Here is a breakdown of the moment that swung the night's momentum.

The situation
In the encore of his Opening Day shutout, Cubs starter Kyle Hendricks was not nearly as sharp against the Reds. Manager David Ross felt it may have been a case of fatigue, especially when Hendricks issued a leadoff walk to Eugenio Suárez in the fourth, followed by a two-run homer to Mike Moustakas.

"I felt like he was running out of steam that fourth inning," Ross said. "When you get a leadoff walk from him, that's uncharacteristic and red flags start to go up a little bit."

Hendricks escaped the fourth without further damage, but he was lifted with one out in the fifth after four batters reached base, culminating in a two-run single for Suárez. With the lefty-swinging Moustakas looming and the Reds holding a 4-0 lead, Ross handed the ball to Brothers.

What the numbers say
Brothers made a strong impression in Spring Training and Summer Camp, flashing a fastball with good life (95-96 mph range) and a solid swing-and-miss slider. The veteran had not pitched regularly in the Majors since 2014, but he earned a job in Chicago's Opening Day bullpen.

The ideal scenario would have been generating a double-play grounder from Moustakas, who had a higher ground-ball rate against lefties (41.9 percent) than righties (33 percent) in 2019. Brothers, meanwhile, entered having held lefties to a .223 average with a 44.4 percent ground-ball rate in his MLB career.

The issue, of course, was that Castellanos was on deck. Without an inning-ending double play, Brothers would be forced to face Castellanos under MLB's new three-batter minimum rules for relievers. That would be good news for the Reds, given that the outfielder crushed lefties to the tune of a .370/.425/.713 slash line in '19.

"It doesn't always work out like that," Reds manager David Bell told Cincinnati reporters. "But, the three-batter minimum, our experience so far is it’s just one more factor, and [it’s] more important to continue to think ahead. But you can only plan for so much."

What happened?
Brothers found himself in a full count against Moustakas after firing a precise fastball to the low-and-away corner. The next fastball was far inside, however, and the Reds second baseman drew a walk to load the bases.

Forced into the battle with Castellanos, Brothers started off with consecutive sliders that tailed low and in for balls. For the third offering, the left-hander fired a 95.6 mph heater above the strike zone, but Castellanos went after it and drove it out to left-center to give the Reds an 8-0 lead.

"The [planned] attack was a little different than it worked out," Ross said, "without giving anything away. And he made us pay for it."

What does it mean for the Cubs?
Above all else, it was a moment that added to a complicated bullpen puzzle that Ross is still trying to sort out. Three-batter minimum or not, the manager is trying to identify arms outside the main late-inning cast that can be trusted in key situations.

"We try to put these guys in the right situations to succeed,” Ross said. "But with that being said, you also have to find guys just to bring in and who can compete, you know? Compete and get the hitters engaged. I've got to look at that a little bit on myself and make sure I'm pulling the right triggers."

While James Norwood and Duane Underwood Jr. pitched well on Wednesday, Brothers and Dillon Maples combined to allow six runs and walk six batters in 1 1/3 innings. That upped the relief corps' Major League-leading walk rate to 21.1 percent on the young season.

"I'm just looking for somebody to get outs, throw strikes," Ross said. "Way too many walks from down there. We've got some guys that have got to kind of step up, and that's some of the stuff that we're finding out here early on, is who's a guy that we can bring in in a big situation and pitch?"