Kruk played in Major League Baseball (MLB) for the San Diego Padres, Philadelphia Phillies, and Chicago White Sox from 1986 through 1995.

On April 13, 1987, Marvell Wynne, Tony Gwynn, and Kruk became the first players in major league history to open their half of the 1st inning with three consecutive solo home runs in a 13–6 loss to the San Francisco Giants.

[4] Unbeknownst to Kruk, who moved out in November to play winter ball in Mexico, Plummer was funding the group's lifestyle by moonlighting as an armed robber, with Hafer serving as his getaway driver.

[4] The FBI informed Kruk of his roommates' criminal activities during spring training in February 1988, approaching him before batting practice with a photo of Plummer taken during a bank robbery.

In his 1993 appearance at the Midsummer Classic, he had a memorable at bat when he flailed wildly at 98 mile per hour fastball from Seattle Mariners pitcher Randy Johnson.

[6] During spring training in 1994, Kruk was diagnosed with testicular cancer (ultimately resulting in the removal of one testicle) after an errant pickoff throw from teammate Mitch Williams hit him in the groin and broke his protective cup.

Moving to the American League to serve as a designated hitter, Kruk signed with the Chicago White Sox on May 12, 1995,[7] batting .308/.399/.390 in his only season with the ballclub.

In the first inning of the White Sox's 8–3 loss to the Baltimore Orioles at Camden Yards on July 30, he singled off Scott Erickson, advanced to and was stranded on third base, removed himself from the game and promptly retired as an active player due to chronic knee soreness.

[7] A quotable character throughout his career who had written a book called I Ain't an Athlete, Lady published in 1994, Kruk turned to broadcasting and commenting on the game.

Kruk coached the National League team in the Taco Bell All-Star Legends & Celebrity Softball Game in Anaheim, California, on July 12, 2010.

[citation needed] Kruk appeared in MLB on ESPN commercials, playing himself as part of moments in baseball history; for example, an old briefcase belonging to Kruk buried in the infield dirt containing a rotten sandwich caused the bugs to attack Karl Ravech dressed up as Yankees pitcher Joba Chamberlain, mocking game 2 of the 2007 ALDS between the Yankees and the Indians.

[18] After moving to Naples, Florida six years prior, Kruk took over the Seacrest Country Day School softball team as the head coach in 2016.