You need to address the reason for the stiffness. Kelly’s stuff is great but you need to recognises why you have a pathological level of tension occurring at your ankle in the first place. Mobility exercises are a form of adjunct therapy. Simply foam rolling and mobilising won’t solve the issue.
Search the joint by joint approach by Boyle and Cook. Based on their anatomical structure some joints are designed to remain generally stable whilst others generally mobile. If we don’t have appropriate stiffness in one area we gain it proximally and distally. Equally if we don’t have appropriate mobility at a joint we gain it proximally and distally. If you don’t address stability deficits in conjunction with mobility deficits and vice versa you are simply treating the symptoms and the problems come back.