Tennis legend Martina Navratilova thinks that Naomi Osaka’s ventures outside of tennis are largely to blame for the 25-year-olds recent poor form.Osaka was last seen in September at the Japan Open which she was forced to withdraw from due to an abdominal injury and fans are eagerly awaiting her return.Osaka burst onto the scene a little under a decade ago and has enjoyed notable success, reaching the world No. 1 spot and bagging four Grand Slams along the way.However, the past two years have been something of a disappointment for Osaka as she has openly struggled with her mental health and various injuries, causing her to plummet to her current …