center field vs keystone

center field

noun
  • The part of a baseball field which is beyond the infield and straight ahead left if you stand on home plate and face the pitcher. 

  • The defensive position in the outfield in the middle, typically played by a player that can run fast. 

  • A central role in some activity that requires speed. 

keystone

noun
  • The combination of the shortstop and second baseman. 

  • A retail price that is double the cost price; a markup of 100%. 

  • A native or resident of the American state of Pennsylvania. 

  • Something on which other things depend for support. 

  • The top stone of an arch. 

verb
  • To distort (an image) by projecting it onto a surface at an angle, which for example causes a square to look like a trapezoid. 

  • To double the cost price in order to determine the retail price; to apply a markup of 100%. 

How often have the words center field and keystone occurred in a corpus of books? (source: Google Ngram Viewer )