In 1926 and 1927 McGregor became the first and as of 2011 West Adelaide's only dual Magarey Medallist and the club's only player to win the award back-to-back.

With the economic privations of the Depression beginning to hit home in 1930, McGregor, along with team mate Bob Snell, the 1929 Magarey Medallist, was lured to Tasmania where the money on offer was significantly better than in Adelaide.

After two seasons as captain-coach of North Hobart in the Tasmanian Football League (TFL) where the team finished as beaten Grand Finalists in both 1930 and 1931, he returned to the SANFL and joined South Adelaide.

He played just two games before standing down as a player but coached the club for the rest of the year with Souths 'winning' the wooden spoon by finishing eighth.

Ken also played tennis at the highest level including representing Australia in three Davis Cup-winning sides (1950, 1951 and 1952) and won the 1952 Australian Open tennis – Men's Singles title at Adelaide's Memorial Drive, as well as the 1951 and 1952 Australian, French and Wimbledon and 1951 US Open men's doubles championships with Frank Sedgman.