Mattern is on board as the Assistant and Sports Performance Coach of the Greenville Liberty. Mattern has been in the industry since her playing days at the University of South Carolina. From 2015-2023, Mattern was the Co-founder and COO of 11.11 Training, a soccer development facility for aspiring college athletes. She brings years of experience competing in professional league across the world, including the Netherlands’ FC Twente, Sweden’s Mallbacken IF and the Atlanta Beat in the U.S. Prior to her professional journey, she was a 4-year starter at USC, 2-year team captain, First-team All-American (first in program history), and 2007 SEC Defensive Player of the Year. Mattern’s ties with the Gamecocks remain strong, as she was inducted into the University’s Athletic Hall of Fame in 2022, only the second women’s soccer player in program history.

Stelling will serve as the Assistant Coach and Video Analyst for the team. This will be her third season as part of the technical staff. Stelling’s main focus is coaching the Mauldin High School Mavericks girls soccer team and teaching mathematics. This is her second year as Head Coach and seventh year on the Mauldin staff. In her first season at the helm, she was named Region 1-AAAAA Coach of the Year and holds an undefeated record of 18-0 and top-five national ranking.

Diaz joins the Liberty SC from Brooklyn FC in the USL Super League, where he specialized in goalkeeper development and tactical training. His coaching career includes goalkeeper coach roles with the New York Cosmos and assistant/goalkeeper coach at Briarcliffe College (2011-14). As a player, he competed for Briarcliffe College (2008-09), Cortulua Professional Soccer Team (2010), FC New York (2011), Real Murcia (2013), and the New York Cosmos (2014-18).