Kolberg grew up at the rugby pitch watching his dad play for Dallas RFC (DRFC). He began playing at 11 years old, but due to the lack of teams in the area his playing time stopped shortly after. At 16 years old he began playing for the DRFC, which jump-started his rugby career.
Kolberg went on to play for Texas Rugby Union U19 and USA U19 from 2002-2004, including the 2003 World Championship qualifier. Continuing to build his career, Kolberg played in the IRB U19 World Championship in 2003 and 2004, being selected MVP of the tournament in 2004. Through the years, Kolberg was part of the 2002 and 2003 Texas Select Side, 2003 and 2004 West 15s side, and 2004 and 2007 West 7s.
Kolberg then made the move to Dunedin, New Zealand. Here, he played for Harbour RFC’s 1st XV side from 2005-2009 with a short break playing for Eagle 7s pool in 2007. Kolberg attended the 15s Eagle XVs camp in 2011 and 2014.
Kolberg has taken part in a multitude of 7 tournaments including Rugbytown 7s for the Republic of Texas 7s team, 2010 Havana 7’s in Cuba, Tiger 7s at Rugbytown 7s and tours to the Central Coast 7s in Australia, Shanghai 7s and twice in the Cancun 7s.
During his time with DRFC from 2001-2021, Kolberg helped the club to many USA 15s Nationals and 7’s nationals. In 2019, Kelly joined the MLR’s Houston SaberCats.