"We wanted to give Edinson an extra day," said Baker. "He's approaching innings that he's never done before. I'm encouraging these young guys to stay on the program, to continue to run and stay strong."
Entering his start on Sunday, Volquez (14-5, 2.86 ERA) had compiled 144 2/3 innings. He threw 178 2/3 frames all of last season, including 34 with the Rangers.
"He needs to learn how to get over that threshold," said Baker. "That goes for all the young players. In the near future, when we're in the playoffs and World Series, they'll still be strong. They'll appreciate it later."
The Reds' revamped rotation is as follows: Johnny Cueto will pitch on Tuesday, Bronson Arroyo on Wednesday, Aaron Harang on Thursday, Fogg on Friday and Volquez on Saturday.
Baker said he approached Fogg prior to Saturday's game to discuss the move and to confirm his availability to pitch in relief this weekend.
"We called him in and said we're going to back him up to Friday," Baker said. "We asked if he would be available Sunday in relief, [and] he said he was available [Saturday night] if we needed him."
Fogg allowed one hit, walked one and had one strikeout in Saturday's game.
"He wanted to go another inning, but I told him he'd done enough," said Baker.
The switch also keeps Harang, who's struggled in his past two starts, on his normal rest.
The 31-year-old Fogg also has struggled, going 2-5 with a 7.71 ERA in 19 appearances, including 11 starts. He's allowed 56 earned runs in 65 1/3 innings.
With the Reds' youth movement in full force, some have speculated that Fogg was being moved out of the rotation. Not so, says Baker.
"If anybody knows how to pitch in Colorado, it's him," the manager said.
Fogg is 12-9 with a 6.06 ERA in 31 appearances at Coors Field.
With the rosters expanding on Sept. 1, the Reds likely will take advantage of it.
"We need another arm," Baker said. "We could use another position player, too."