According to US coach Ronnie Shields, former heavyweight boxing champion Anthony Joshua is switching trainers for the rematch with Oleksandr Usyk. Following his loss to Usyk in September, AJ is presently in America and has been observed in a number of gyms. At the time of the Usyk fight, many pundits questioned AJ’s tactical approach, as he sought to outbox the smaller technical Usyk rather than use his size and strength advantages. AJ shared Snapchat videos of himself visiting Joshua Buatsi at Virgil Hunter’s gym in Hayward, California, last week. On Sunday, October 17, a video surfaced of Jo…