about-face vs whole new ballgame

about-face

verb
  • To turn 180 degrees to face the opposite direction. 

  • To change opinion or attitude drastically. 

noun
  • A reversal in direction; a reversal of attitude or opinion. 

  • An abrupt turn to face the opposite direction. 

whole new ballgame

How often have the words about-face and whole new ballgame occurred in a corpus of books? (source: Google Ngram Viewer )