CHICAGO -- It's only August, but the Cubs are starting to play like it's September.

Chicago already has three top prospects playing more or less every day, with first baseman Anthony Rizzo, center fielder Brett Jackson and third baseman Josh Vitters. Plus, the Cubs are continuing to play hard despite being out of the playoff picture, beating the first-place Reds on Thursday to extend Cincinnati's losing streak to five games.

Manager Dale Sveum said his team will continue to compete hard and play the game the right way for the rest of the season.

"You'd always want that done if you were on the other end of things, to help the other teams out or knock people out of the playoffs and all that," Sveum said. "When you're not in the pennant race, those are the things you play for, too, as a player."

Before Thursday's victory, the Cubs' eight-game losing streak nullified an 18-10 stretch during which they played their best baseball of the season. The skid began on July 31 -- when the Cubs traded pitchers Ryan Dempster and Paul Maholm, as well as catcher Geovany Soto.

Since then, Chicago has been in rebuilding mode, adding Jackson and Vitters to the roster on Sunday. Sveum knows the coming months may bring growing pains, but going through them also is the best way to assess and develop the youngsters.

"Tough times or not, you have to be able to show the ability to handle adversity and all those kinds of things," Sveum said. "That's part of the whole maturing and the evaluation that we're going to be doing, is the evaluation of the character of people, as well as the talent we have."

With Rizzo, Jackson, Vitters and other young players already with the Cubs, Sveum admitted the club likely will have fewer September callups than usual.

Those who do join that trio likely will play, as the Cubs continue to look to build toward the future. And just because some guys might get an extended look, that doesn't guarantee them a roster spot for 2013, Sveum said.

"The development, the taking a look-see at everything, the guys that are here -- obviously, what's going to be out there, all kinds of things can happen during the winter," Sveum said. "I don't care who you are in this organization. We're all doing a lot of evaluating right now and seeing what we're going to need and who needs to develop more."

Clevenger takes responsibility for ejection

CHICAGO -- Cubs manager Dale Sveum was upset Thursday night after catcher Steve Clevenger was ejected in the fourth inning by home-plate umpire Jeff Nelson for arguing balls and strikes while up to bat.

Clevenger said Friday he knew he was wrong, and he apologized to Sveum after a 5-3 comeback win over the Reds.

"Dale was right: I can't get ejected in that situation for that," Clevenger said. "I went up and apologized to Dale last night for getting ejected. Like I said, won't happen again, can't happen."

With a runner on first, one out and the Cubs trailing, 3-1, Reds right-hander Mike Leake threw a 1-1 fastball to Clevenger, who took the outside pitch, which was ruled a strike by Nelson.

The previous pitch, called a ball, was in a similar spot, and TV audio picked up Clevenger telling Nelson, "That was the same [gosh darn] pitch."

Clevenger -- who also appeared to be upset when he was called out looking in the second inning -- was then ejected.

"The ball was outside, and the next pitch was the same exact pitch, I thought, and he called it a ball," said Clevenger, who reiterated he was sorry.

"In the heat of the moment, you say things you regret," Clevenger said. "I'll talk to Jeff. I'm sure I'll have him behind the plate sometime this year or somewhere."

Worth noting

• Right-hander Lendy Castillo was in the Cubs' clubhouse Friday morning, and Sveum said he likely will be activated from the 15-day disabled list at some point this weekend. Castillo has been out since May 16, retroactive to May 14, with a left groin strain.

• Right-hander Chris Volstad's quality start Thursday, coupled with Jeff Samardzija's on Wednesday against San Diego, marked the first consecutive quality starts turned in by Cubs starters since July 28-29, when Samardzija and Paul Maholm did so.