Eddie Robinson at Grambling. Mike Krzyzewski at Duke. Gregg Popovich with the Spurs. It’s hard to underestimate the impact these coaches have had on their organizations. But are coaches always an X factor? Consider the Golden State Warriors. Dominating as they have been under Steve Kerr’s steady guiding hand, they have been every bit as successful during his two extended absences. So, how much do coaches actually matter? Two researchers from the University of Chicago just might have the answer.