| | | Friday, August 15th, 1980 | | Placed SP Danny Owens on the 15-day disabled list. |
| Wednesday, July 23rd, 1980 | | Activated CL Kerry Johnson from the disabled list. |
| Wednesday, July 16th, 1980 | | Activated RF Manny Gallegos from the disabled list. |
| Monday, June 23rd, 1980 | | Placed CL Kerry Johnson on the 15-day disabled list. |
| Sunday, June 15th, 1980 | | Promoted SP José Ledezma to Double A San Antonio. | | Drafted LF Guus Schumacher in the 1980 first-year player draft (Round 6, Pick 5, 109th overall pick). | | Drafted MR Domingo Álvarez in the 1980 first-year player draft (Round 7, Pick 5, 130th overall pick). | | Drafted RF Mike Miller in the 1980 first-year player draft (Round 8, Pick 5, 150th overall pick). | | Drafted MR Robert Reed in the 1980 first-year player draft (Round 9, Pick 5, 170th overall pick). | | Drafted MR Gerald Lewis in the 1980 first-year player draft (Round 10, Pick 5, 190th overall pick). |
| Wednesday, May 14th, 1980 | | Placed MR Keith Washington on the 15-day disabled list. |
| Friday, May 2nd, 1980 | | Placed MR Michael Schmidt on the 15-day disabled list. |
| Wednesday, April 16th, 1980 | | Placed RF Manny Gallegos on the 15-day disabled list. |
| Monday, October 1st, 1979 | | 3B Javier Mata becomes a free-agent. |
| Thursday, August 23rd, 1979 | | Signed Manager Carlos Pérez to a 3-year contract extension. | | Signed Pitching Coach Larry Hill to a 2-year contract extension. | | Hitting Coach Josh Higgins leaves the team, his contract was not renewed. | | Released SP António Torres. |
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