Mendoza remained with the Pirates as a defensive replacement through 1978, playing some second and third base as well.
Following the season, Mendoza was sent to the Texas Rangers in a blockbuster deal along with Larry Cox, Rick Honeycutt, Willie Horton, and Leon Roberts for Brian Allard, Rick Auerbach, Ken Clay, Jerry Don Gleaton, Richie Zisk, and Steve Finch.