James Justin Acker (born September 24, 1958) is a former Major League Baseball pitcher from 1983 to 1992. He played college baseball at the University of Texas.
Acker was drafted in the first round by the Atlanta Braves in the 1980 Major League Baseball Draft and was a member of the Toronto Blue Jays teams that won the 1985, 1989, and 1991 American League East division. He also played for the Seattle Mariners.
He was drafted by the Atlanta Braves in the first round (21st selection) of the 1980 Major League Baseball Draft. On December 6, 1982 he was drafted by the Toronto Blue Jays from the Atlanta Braves in the 1982 Rule 5 Draft. He pitched for the Jays for four years performing mainly as a relief pitcher.
On July 6, 1986 Acker was traded by the Blue Jays to the Atlanta Braves for pitcher Joe Johnson. He spent four years with the Braves, compiling a record of 7-27 with 16 saves and a 3.71 ERA in 169 games.
On August 24, 1989 Acker was traded by the Braves back to the Toronto Blue Jays for Francisco Cabrera and Tony Castillo.
Acker spent part of the 1989 year and the complete 1990 and 1991 seasons back with the Blue Jays. In his entire seven-year career with the Jays he compiled a record of 26-22 with 14 saves and an ERA of 4.07 in 281 games. On October 31, 1991 he was granted free agency.
Acker signed as a free agent with the Seattle Mariners on February 2, 1992. He appeared in 17 games with the M's, compiling a 5.28 ERA, before he was released on July 21, 1992.
Acker ended his baseball career after 6 appearances with the Oklahoma City 89ers, the Texas Rangers Triple-A affiliate, in 1993.