Cubs acquired RHP Casey Weathers and 3B Ian Stewart from the Rockies for OF Tyler Colvin and INF DJ LeMahieu.
Casey Weathers will need Tommy John surgery after being diagnosed with a torn UCL in his right elbow.
Casey Weathers was diagnosed with a strained flexor muscle in his right forearm, but the Rockies will have him examined in Denver.
Casey Weathers left his AFL appearance Thursday holding his elbow after throwing a pitch.
Double-A Tulsa's Casey Weathers pitched a perfect inning on Wednesday to lower his ERA to 1.96.
Casey Weathers, the eighth overall pick in the 2007 draft, turned in a perfect inning for Double-A Tulsa on Thursday.
Rockies selected Vanderbilt RHP Casey Weathers with the eighth pick in the 2007 draft.