He played nine years in Major League Baseball for the Detroit Tigers (1976–1980), Texas Rangers (1981–1983), and Oakland Athletics (1984).

[1] In December 1980, the Tigers traded Wagner to the Texas Rangers in exchange for relief pitcher Kevin Saucier.

[1] During 1982 spring training, Wagner beat out Mario Mendoza and began the season as the Rangers' starting shortstop.

In April 1982, Steve Pate of the Fort Worth Star-Telegram wrote that Wagner was "playing some of the best shortstop in the history of the organization.

"[9] On May 17, 1982, he was stretching prior to a game when he was hit on the back of the head by a baseball thrown by Chicago White Sox Jerry Koosman.

[10][11] Wagner reported to the team in 1983, but Bucky Dent won the starting shortstop job, and Texas manager Doug Rader declined to play him even as a backup.

[13] He compiled a .230 batting average for Oakland and appeared in his final major league game at age 30 on September 30, 1984.

Defensively, he appeared in 408 games (327 at shortstop) and tallied 469 putouts, 852 assists, 154 double plays, 61 errors, and a .956 fielding percentage.