For 108 straight days, the Chicago Cubs possessed a share of first place in the division.

The Cubs’ consistency, especially offensively, kept them in control despite injuries to the rotation while owning the best run differential in the majors. The Cubs’ hold on the top of the National League Central ended, at least for one day, with Monday’s 12-4 loss to the Kansas City Royals coupled with the Milwaukee Brewers’ 11th consecutive victory.

Their run in first place, dating to April 4, took a sizzling stretch by the Brewers to dethrone the Cubs (59-41) and sets up a huge series next week in Milwaukee. But the way their loss unfolded in Monday’s series opener against the Royals created a frustrating backdrop to a stretch where the Cubs have tried to focus on their play while Milwaukee mounted a charge up the standings to the best record in baseball.

The hearty boos during the fifth inning from the crowd of 38,117 at Wrigley Field marked an amplification of Cubs fans’ frustrations. Right-hander Ben Brown, called up from Triple-A Iowa before the game, entered in the second following opener Ryan Brasier. Carson Kelly’s solo home run and Matt Shaw’s three-run home run in the second gave Brown a 4-1 lead to work with.

A two-out, two-run home run from Royals catcher Salvador Perez, who ambushed Brown’s first-pitch fastball, cut the Cubs’ lead to one run. That slim margin of error became problematic in the fifth. The Royals (49-52) tallied three consecutive hits to take the lead, scored a run on Kelly’s throwing error to second base as Bobby Witt Jr. attempt to steal, and tacked on another run in that same at-bat when Brown uncorked a errant changeup for a wild pitch to create a 7-4 deficit for the Cubs.

Right-hander Chris Flexen took over in the sixth and gave up five runs in his three-inning appearance to put the game out of reach.

Within the fifth-inning sequence, Brown deflected Witt’s one-out infield single, a ball that had a .060 expected average. Manager Craig Counsell called that the play of the game.

“If we make that play, there’s a chance to get out of that inning with it a tie game,” Counsell said. “Now that still, we’ve given up four and in a four-inning stretch and probably got to do better than that to expect a win generally. So that’s where we’re at.”

The Cubs need more reliability from Brown, who’s shown dazzling flashes of greatness and then at-bats or innings that get away from him. Those inconsistencies become more heightened as the Cubs navigate rotation this year and try to manage workloads, such as Matthew Boyd’s. Too many mistakes over the middle of the plate continue to haunt Brown. He gave up seven hits and seven runs (six earned) in four innings on Monday.

Brown tried to focus on the positives from his outing, including how he handled Witt.

“I felt locked in,” Brown said of the four-run fifth inning. “It’s just baseball today. It’s just unfortunate that baseball keeps baseballing me a lot pretty often. And I have to figure out a way for it to not do that.”

As the days keep moving closer to October, Brown wants to help the Cubs win. He understands that too often this year it hasn’t been happening.

“I’m kind of a non-contributor when things like (what) happened tonight and it’s unfortunate,” Brown said. “So whatever opportunities are ahead of me, I’ve got to be better to earn that and to have that opportunity.”

Before Monday’s game, Counsell didn’t sound like the Cubs were inclined to give Brown a look out of the bullpen in shorter relief appearances at this point.

Photos: Chicago Cubs lose to the Kansas City Royals, 12-4

“I understand the calendar’s shorter, I think our available starter situation isn’t completely full right now, so I would say no to that question as we sit here right now,” Counsell said. “Obviously things can change, but right now he’s going to pitch in bulk or length.”

The Cubs’ trade deadline acquisitions could alter Brown’s role. As much as the Cubs have tried to make Brown as a starter work, it might end up being in both sides’ best interest to turn him into a true reliever at some point this season and see if he can handle high-leverage situations.

“It’s cool to be on a team that’s in a winning position, and I’m just having my hands open to anything that’s coming down my way,” Brown said. “So whatever it is, it’s just a fun time to be a Cub and fun time for Cubs fans, we’re playing really good baseball. It’s encouraging to be part of it and I’ve got to start helping out a little bit better.”