MS Dhoni has a calf injury. He has not rushed back. Partly because Chennai Super Kings are managing him carefully at 44. But partly, those inside the dressing room say, because Kartik Sharma has made it complicated. It was not long ago that Stephen Fleming was sceptical about young blood. As CSK fell behind other teams in batting approach last season, Fleming held his ground — sample size too small, he said. Weeks later he had changed his mind. Beyond Abhishek Sharma , Priyansh Arya and Vaibhav Sooryavanshi, there were more. Kartik was among them — spotted mid-season by CSK’s scouting team, added to their pool as a development player, ineligible for the auction but too good to ignore. A year on, he is making that scouting look shrewd. Kartik is 19, from Bharatpur, and not the biggest or burliest of batters. What he has is one specific thing, and he has built his life around it.…