 It demonstrated a valuable alternative to management's usual approach of just repeating the "Usual Fixes" such as sales training or CRM, which typically have little measurable or sustainable effect on productivity.The book earned 4.5 stars on Amazon and sold more than 21k copies.Brent Wahba, an engineer with a background in Lean at GM and Delphi Automotive, also saw that root cause thinking had not yet penetrated the culture of sales and marketing management.