Our writers below further examined the Heat-Celtics series, answering questions about their keys to victory, potential X-Factors, predictions and more! The Miami Heat and the Boston Celtics will tip-off their Eastern Conference Finals showdown Tuesday at 8:30 p.m. on ESPN, the first of what could be an electrifying seven-game series between the two semi-rivals. This will be the fifth ever time the two teams have played each other in the playoffs, a series that dates back to the 2009-10 season. Miami has bested Boston in three of the previous four playoff meetings, the most recent coming in the 2019-20 bubble…