He split the 1969 season between the Double-A Columbus White Sox and the Triple-A Tucson Toros, playing just 11 games at each level.

McKinney was traded from the White Sox to the New York Yankees for Stan Bahnsen at the Winter Meetings on December 2, 1971.

[4] Almost immediately after the Yankees acquired him, while playing winter ball, he suffered second-degree burns at a beach party in Puerto Rico.

He began the 1972 season as the Yankees regular third baseman, but was unable to handle the "hot corner," committing a record tying four errors in an 11-7 loss to the Boston Red Sox at Fenway Park.

McKinney was sent to the Oakland Athletics on December 1, 1972, to complete a deal made a week prior on November 24 in which the Yankees acquired Matty Alou for Rob Gardner.

He spent the entire 1976 season with Tucson, batting .317 with career highs in home runs (22) and RBI (95), but did not get a call to the majors.