Ruck began his career on the Chicago stage appearing in various off-Loop productions in the early 1980s. He also worked in regional theater and off-Broadway before making his 1985 Broadway debut in Neil Simon's autobiographical "Biloxi Blues", co-starring Broderick. Ruck originated the role of Carney, the soldier who aspires to be the next Perry Como.
Segueing to the small screen in the mid-80s, Ruck appeared in several busted pilots, guest shots and TV-movies. He had stints as a regular in a series of unsuccessful TV comedies in the 90s including "Going Places" (ABC, 1990-91), as a socially maladjusted TV writer, "The Edge" (Fox, 1992-93), as an ensemble member for sketch comedy and "Daddy's Girls" (CBS, 1994), as Dudley Moore's son-in-law and "the world's most boring ophthalmologist". That last failure was followed by the short-lived "Muscle" (WB, 1995), a serialized sitcom in which he played a sex-obsessed shrink.
On the big screen, Ruck's pre-blockbuster feature credits included the road comedy "Three for the Road" (1987), "Three Fugitives" (1989) and "Young Guns II" (1990). The latter offered the atypical role of a soft-spoken, peaceful farmer who joins Billy the Kid to avenge the loss of his farm. Ruck resumed playing against more glamorous leads and impressive special effects as a supporting player in Jan De Bont's "Twister" (1996).