Horford had scored a team-high 14 points before he was ejected.
The call was a controversial subject on social media. Many believed that Horford should not have been assessed a Flagrant 2 foul and that the ejection was unwarranted.
"Horford threw an unnecessary and excessive forearm/elbow to Dellavedova, making contact above the shoulders, therefore a flagrant 2 foul was called on Horford," the NBA's officiating Twitter account explained.
Many current and former NBA players shared their thoughts on the call on Twitter. The Cavaliers—led by LeBron James's 37 points, 18 rebounds, and 13 assists—beat the Hawks 114–111 in overtime. Cleveland took a 3-0 lead in the series and is one win away from an NBA Finals appearance.