Mass was taken 182nd overall by the Capitals in the 2017 NHL Entry Draft.

The right-handed defenseman had 13 goals and 45 points between stints with Fairbanks of the NAHL and Elk River in the Minnesota high school ranks (scoring 29 points in 25 games at the latter). The 6-foot-1, 185-pound Minnesotan will continue to develop in the junior ranks for the foreseeable future as Washington has plenty of organizational depth on defense.