The first round of the NBA playoffs has been exciting for fans, and the numbers prove it. The four-game series between the Boston Celtics and Brooklyn Nets averaged 4.8 million viewers across ABC, TNT, and ESPN, making it the most-viewed first round matchup series since the Houston Rockets and Golden State Warriors faced off in 2016. The Eastern Conference’s second round tips off Sunday, with a huge semifinal matchup between Boston and the Milwaukee Bucks. Be sure to check out the rest of our NBA content. The Matchup This is the battle in the Eastern Conference the fans have been waiting for. …