Cubs activate Barney from 15-day DL
To make room, the Cubs designated second baseman Brent Lillibridge and reliever Hisanori Takahashi for assignment, and optioned right-hander Rafael Dolis to Triple-A Iowa.
Barney missed the Cubs' first 12 games of the season after suffering a lacerated left knee late in spring training. Lillibridge played in nine games for the Cubs and had one hit in 24 at-bats.
Ransom appeared in five games for San Diego and was hitless in 11 at-bats.
The Cubs hope those moves will help their defense and a struggling bullpen, problems president of baseball operations Theo Epstein is confident won't be as troublesome when Wrigley Field undergoes a $500 million renovation.
''We need revenues to increase in order for us to execute our baseball plan,'' Epstein said. ''We expect them to.''
Chicago entered Tuesday with a 4-8 record.
''We are off to a slower start than we would've liked,'' Epstein said. ''Some sloppy play that we need to eradicate sooner than later.''
Gregg spent spring training with the Los Angeles Dodgers and has experience as a closer, including saving 23 games for the Cubs in 2009.
Loe was claimed off waivers on Sunday from the Seattle Mariners and has a 1-1 record and 10.80 ERA in four appearances.
Takahashi was in his first season with the Cubs and had a 6.00 ERA in three appearances. Dolis was called up Saturday and pitched a scoreless one-third of an inning.
The Cubs are already on their third closer after struggles by Carlos Marmol and a forearm injury to Kyuji Fujikawa.
Entering Tuesday, the Cubs' bullpen had blown four of seven save opportunities.
''It's always bad when you can't close out games, I don't think there's any question about that,'' Cubs general manager Jed Hoyer said. ''I think that, if you want to look for a silver lining, we've been in a lot of games and we should have won more of them.''