HOUSTON -- As Aroldis Chapman continues to transform into a closer, manager Dusty Baker said he's been impressed with how the left-hander has improved at pitching on a second straight day.

"He's getting better at throwing back the second day with the same stuff that he has the first day," Baker said. "Your body gets acclimated to whatever role that you're in after a period of time."

Chapman has pitched on consecutive days four times in the month of July, entering Monday. He hasn't given up a hit on zero days rest all month. On the season, Chapman has a 0.90 ERA in 10 innings on zero days rest, a 0.00 ERA in 12 1/3 innings on one day of rest and a 2.70 ERA in 23 1/3 on two or more days rest.

Baker again addressed the team's decision to keep Chapman in the bullpen.

"We needed him in that role. That's the thing," Baker said. "There was a ton of debate about should he be starting early in the season, but where would we be right now without him? ... He's been involved in half our wins almost. I just hate to think where we'd be without him, as our setup man first and then our closer."

Entering Monday, Chapman had 17 saves and 86 strikeouts in 45 2/3 innings. The Reds are 35-7 when he makes an appearance.

Heisey starts over Bruce in matchup vs. Wandy

HOUSTON -- The last time the Reds faced Astros starter Wandy Rodriguez this season, manager Dusty Baker decided to start Chris Heisey over regular right fielder Jay Bruce.

Bruce, 2-for-29 against the left-hander for his career, didn't start again on Monday against Rodriguez. Heisey took Bruce's spot in right field, like he did on June 2 at Minute Maid Park, and batted seventh. He entered Monday's game 4-for-11 against Rodriguez with a homer and three RBIs.

Baker said Bruce, originally from Beaumont, Texas, didn't lobby to start.

"When I say no, it's usually no," Baker said. "And he knows."

Monday was just the second time this season that both of the Reds' All-Star hitters, Bruce and Joey Votto, were out of the lineup. Votto has been on the disabled list since July 17 as he recovers from arthroscopic surgery to repair the torn medial meniscus in his left knee. The duo also didn't start on July 17 against the D-backs.

"This is time for some of the extra guys to play, to stay sharp and to keep my regular guys strong," Baker said. "The dog days are right around the corner."

After the three-game series with the Astros, the Reds have an off-day on Thursday before playing 17 games in 17 days.

Worth noting

• Right-handed reliever Jose Arredondo was available to pitch on Monday after being hit by a ball on his right forearm on Saturday against the Brewers.

Entering Monday, Arredondo had a 2.29 ERA in 39 1/3 innings. He has 45 strikeouts.

• After having outfielder Drew Stubbs bat in the leadoff slot and shortstop Zack Cozart in the two-hole in five of the last seven games, manager Dusty Baker decided to swap Stubbs and Cozart in the lineup for Monday's game.

Cozart has led off in 66 of the Reds' 96 games this season. Stubbs has batted second 51 times.

• Right-hander Nick Travieso, the Reds' first-round pick in the 2012 First-Year Player Draft, made his professional debut for the Rookie League Reds on Sunday. He threw one inning, retiring the side in order with one strikeout.

Travieso, out of Archbishop McCarthy High School in Fort Lauderdale, Fla., was the 14th overall pick.