lacking vs third string

lacking

adj
  • Missing or not having enough of (a good quality, etc). 

noun
  • The absence of something; a lack. 

third string

adj
  • Of a decidedly lower quality or condition. 

noun
  • A unit of players that plays behind the first and second strings; a junior varsity team. 

How often have the words lacking and third string occurred in a corpus of books? (source: Google Ngram Viewer )