After a day or two of discussions, Mike Piazza began a rehab assignment at Triple-A Sacramento on Friday night -- no catching duties required. The plan now is to have Piazza DH at Triple-A Sacramento and Class A Stockton for the next week to 10 days, which will give him plenty of time to show that he's healthy and also will buy the A's some time before having to make a roster decision. "Hopefully, in that time, Mike gets his swing back and one of two things are going to happen,'' said Piazza's agent, Dan Lozano of Beverly Hills Sports Council. "Either Oakland activates Mike, or they're going to trade him to a location Mike is OK with.'' That's because, according to Lozano, Piazza has a say in potential destinations if general manager Billy Beane decides to move him. "We don't have a no-trade clause, but Billy, Mike and I agreed prior to Mike's signing that we have a gentleman's agreement that Billy would not trade Mike anywhere that Mike was not OK with,'' Lozano said.