beat to a pulp vs beat up on

beat to a pulp

verb
  • To beat up (a person) more than usually severely. 

  • To defeat severely in various, even non-contact, competitive sports. 

beat up on

verb
  • to hurt someone by hitting or kicking them many times 

  • to criticize someone unfairly 

How often have the words beat to a pulp and beat up on occurred in a corpus of books? (source: Google Ngram Viewer )