View the original article to see embedded media. Tuesday’s 98-95 loss in South Beach highlighted the growing pains of a rookie head coach taking over a team with championship aspirations. Joe Mazzulla has done an excellent job this season. But there are two areas he struggles with most: managing minutes and having a feel for when to call a timeout, as opposed to challenging the Celtics to play through runs by the opposition most of the time. Mazzulla might disagree, but in the fourth quarter of Boston’s loss to the Heat, the visitors got burned by both. Jayson Tatum played…