Tim MacMahon reports the Mavericks plan to select Cooper Flagg with the top pick in the NBA Draft. (0:55)Open Extended ReactionsAfter making the biggest leap in NBA draft lottery history to land the No. 1 overall pick, the Dallas Mavericks plan to select Duke forward Cooper Flagg and will not entertain the possibility of trading away the pick for a proven superstar, sources told ESPN. While Dumont has given Harrison great leeway to run basketball operations, the governor has final decision on all personnel matters. "Every time he's put in a situation that everyone wondered if he could succeed, he's succeeded and then some."