I am skeptical about this device becoming a game changer in tennis. I played tennis for a while and what really helped me then was video analysis. While data is helpful, it's not as helpful as video. If the wearable could depict my form and technique from data, that'll be a game changer. For game improvement, we don't lack knowledge. After playing any game for a while, we'll know our limitations - but to tide over those limitations you need hours and hours of practice along with a coach. During those rigorous practice hours, your mind gives up and you just want to quit, but your coach won't let you do that :).