Wrenn was considered "one of Harvard's greatest all-around athletes,"[3] a star player at football, ice hockey, and baseball.

[4][3] Wrenn played a small role in the formation of college ice hockey in the United States.

[5] In the fall of 1892, Wrenn and fellow tennis champion (and doubles partner) Malcolm Greene Chace played in an international tennis tournament in Niagara Falls, New York,[5] where they met some Canadian athletes who invited them to return the next winter to learn about their sport of ice hockey, which differed from the game of ice polo which was then played in American colleges.

[5] Wrenn and Chace gathered some friends from other northeast colleges including Cornell University and returned to Canada over Christmas break 1894-95 for a series of hockey matches.

He was arrested in 1914 when the car he was driving ran over and killed Herbert George Loveday, the choir director of St Mary's Church in Tuxedo Park, New York.