ball of fire vs eager

ball of fire

noun
  • A person who is especially hard-working, high-achieving, ambitious, or active. 

eager

adj
  • Not employing lazy evaluation; calculating results immediately, rather than deferring calculation until they are required. 

  • Desirous; keen to do or obtain something. 

How often have the words ball of fire and eager occurred in a corpus of books? (source: Google Ngram Viewer )