Fitzpatrick explained that he was been working with his coach, Mike Walker, and biomechanist Sasho Mackenzie on a system called The Stack. Without diving too deep, it uses a speed stick and an app to improve sequencing and swing speed. “I’ll be honest, it’s worked wonders,” Fitzpatrick said Sunday.  In this episode, we learn just what this team did before the US Open victory and what they will continue to do in the future!