The slick-fielding South African singled in his first plate appearance last month, but batted .222 without a homer in 28 games prior to the demotion.
Ngoepe picked up baseball as a child because his family lived in the clubhouse of a men's league ballpark where his mother worked. His younger brother, Victor, is also a Pirates minor leaguer.
The elder Ngoepe is headed to Triple-A Indianapolis. Manager Clint Hurdle says he told the 27-year-old to work on his two-strike approach and small-ball hitting. Hurdle told him that if he shows those skills next time he comes to the majors, "you can stay."