During the offseason before the 2016 season, Mastroeni visited London, spending several days watching Arsenal and Tottenham train. While there, he analyzed the coaching styles of Tottenham's Mauricio Pochettino and Arsenal's Arsène Wenger, before he traveled to Orlando to attend a supplementary coaching course. Mastroeni helped the Rapids establish a team identity in 2016, a defensive based team which operated out of the 4-2-3-1 formation. This identity helped the Rapids to their best regular season record of all time, with a franchise low 6 losses and a franchise high of 58 points. The team allowed an MLS low 32 goals in 2016. Mastroeni finished second in voting for the annual MLS Coach of the Year award.