Sweeney, 28, returns after suffering a left rib fracture when he crashed into the center-field wall on June 29 in Seattle. He was batting .295 at the time with four home runs and 15 RBIs in 44 games.
"To be able to play every day again was huge," Sweeney said of the opportunity he had before he was injured. "To have a freak thing happen like that is definitely not something you want to have happen."
Will he be careful in the outfield?
"I'll remain aggressive," he said. "It's a bone that should be healed. I'm still going to run into the wall if I have to -- unfortunately."
"Hopefully his elbow doesn't get in the way of his ribs this time [if he does]," Cubs manager Dale Sveum said when told Sweeney will keep running into walls. "It's nice to have those guys back, and get the left-handed bats in there."
Sveum plans to rotate Sweeney, Brian Bogusevic, Junior Lake and Nate Schierholtz in the outfield, with Schierholtz getting the majority of playing time against right-handed pitchers.
Valbuena, 27, was placed on the disabled list on Aug. 4 with a right oblique strain. He was batting .225 with 13 doubles, nine home runs and 31 RBIs in 89 games. He will share third with Donnie Murphy, who led the team with eight home runs in August, and Cody Ransom.
"I want to finish strong, that's what I'm looking for now," Valbuena said. "Everybody works a lot and everybody's focused to win the last month and have a good record. That's important right now."
The Cubs aren't set at third base next season. Valbuena could be a candidate.
"I have to be ready for spring and see what decision they make," he said.
Cabrera, 24, returns for his second season with the Cubs after splitting this year with Double-A Tennessee and Iowa. He combined to go 10-6 with a 3.79 ERA in 33 appearances, including 18 starts. He made his Major League debut with the Cubs last August, going 1-1 with a 5.40 ERA in 25 relief appearances.
Sanchez, 24, went 0-1 with a 5.68 ERA in four relief appearances with the Cubs this season. He was claimed off waivers from the Cardinals on May 21 and combined to go 1-1 with three saves and a 3.38 ERA in 33 relief appearances between Triple-A Iowa and Triple-A Memphis.
With the moves, the Cubs' 40-man roster is at 40 players. They are expected to add a few more pitchers once Iowa's season ends on Monday.