| Friday, September 19th, 1980 | Placed MR Harry Henderson on the 60-day disabled list. | Monday, September 15th, 1980 | Activated LF Manny Olivarez from the disabled list. | Monday, August 18th, 1980 | Placed MR Deron Byers on waivers. | Saturday, August 16th, 1980 | Released RF Esteban Ramírez.(Career-ending injury) | Tuesday, August 12th, 1980 | Placed 2B Paul Thames on the 9-day disabled list. | Recalled 2B Clint Forman from Triple A Ajax. | Signed Xiu-tou Gao to a minor league contract with a signing bonus of $156,000. | Saturday, August 9th, 1980 | Signed Steve Clay to a minor league contract with a signing bonus of $26,400. | Friday, August 8th, 1980 | Signed Paul Pierson to a minor league contract with a signing bonus of $25,500. | Thursday, August 7th, 1980 | Signed Ric Marks to a minor league contract with a signing bonus of $172,000. | Tuesday, April 8th, 1980 | Placed SP Lynn Hopkins on the 9-day disabled list. | Friday, April 4th, 1980 | Activated MR Joel Clark from the disabled list. | Wednesday, March 19th, 1980 | Placed MR Joel Clark on the 9-day disabled list. | |
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