California Angels right-hander Bert Blyleven underwent his second shoulder operation in less than a year yesterday and will require at least nine months of rehabilitation, the team said. The surgery began as an arthroscopic procedure, but orthopedists Lewis Yocum and Frank Jobe discovered that Blyleven, 40, had suffered further tearing in his right rotator cuff since an operation last fall.

* CUBS: Rick Sutcliffe is back, and manager Don Zimmer said he will be reactivated tomorrow and will start at Pittsburgh that night.