A speedy switch-hitter who hit at least .277 with occasional power for nine straight seasons (1979-87), Mumphrey was a defensive liability. He played his first full ML season in 1976, and in 1977 he hit .287 with 22 stolen bases as the Cardinals’ centerfielder but also committed nine errors. He was traded to Cleveland with John Denny for Bobby Bonds after hitting .295 in 1979, then was traded to the Padres before the 1980 season began. Mumphrey hit .298 with a career-high 52 stolen bases in 1980, but he led NL outfielders with 11 errors and went to the Yankees in a six-player deal that brought Ruppert Jones and Tim Lollar to the Padres. Mumphrey led AL outfielders with eight errors in 1981 while hitting .307, and in 1982 hit .300 with nine home runs, then was traded to Houston for Omar Moreno. He hit .290 and .277 in two seasons with the Astros before a final trade sent him to the Cubs for Billy Hatcher. Mumphrey became an accomplished pinch hitter and hit .304 as a part-time player in 1986 and .333 with a career-high 13 HR in only 309 at-bats in 1987, but was released after hitting .136 in 1988.