Tim S. Grover was the trainer of some of the greatest elite NBA players and Hall of Famers such as Micheal Jordan, Kobe Bryant and Dwyane Wade. In his 2013 book, Relentless: From Good to Great to Unstoppable, Grover describes the mindset of the greatest elite champions. He categorized competitors into three types: Cooler, Closer and Cleaner.

Grover shares various stories and characteristics of the various competitor types. The book Relentless: From Good to Great to Unstoppable, is based on the 13 qualities exhibited by most cleaners.