Gaddy was a highly sought after recruit for Washington: he was ranked the No. 2 point guard in the class by ESPN behind John Wall and was a McDonald's All-American in 2009. His collegiate career got off to a slow start as a backup to Venoy Overton and Isaiah Thomas. As a sophomore, he moved into the starting lineup and averaged 8.5 points and 3.8 assists before an ACL tear in January 2011 ended his season. Gaddy improved those numbers to 8.1 points and 5.2 assists as a junior. He led the Huskies to two NCAA tournament berths. As a senior, he averaged 11 points and 3 rebounds per game.
Professional career
After going undrafted in the 2013 NBA draft, Gaddy joined the Charlotte Bobcats for the 2013 NBA Summer League. On September 23, 2013, he signed with the Bobcats, but he was later waived on October 10. On November 1, 2013, he was selected by the Iowa Energy in the second round of the 2013 NBA Development League Draft. His rights were then traded to the Santa Cruz Warriors on November 5, and then the Maine Red Claws on November 6. In 46 games for Maine in the 2013–14 season, he posted averages of 9.0 points, 5.0 assists and 3.2 rebounds per game, while shooting.420 from three-point range. He had the fourth triple double in Red Claws history on March 2 when he recorded 23 points, 11 assists and 10 rebounds against the Austin Toros. Gaddy joined the New Orleans Pelicans for the 2014 NBA Summer League and averaged 5.2 points and 3.2 assists in five games. On July 30, 2014, he signed with Italian team Virtus Bologna for the 2014–15 season. In 33 games for Virtus, he averaged 7.3 points, 3.0 rebounds and 3.7 assists per game. On May 26, 2015, he signed a two-year contract extension with the club. Following the 2016–17 campaign where he won the Latvian championship and made the VTB League playoffs with VEF Riga, Gaddy signed with s.Oliver Würzburg of the German Basketball Bundesliga. He averaged 8.1 points, 4.6 assists, 2.5 rebounds and 0.92 steals per game, shooting 48.1 percent from the field. On September 23, 2018, Gaddy signed with the Oklahoma City Thunder. After playing in four preseason games, Gaddy was waived on October 12. Gaddy was added to the Oklahoma City Blue training camp roster on October 23, 2018. On January 23, 2020, Gaddy registered 12 points, a G Leage season-high 20 assists, and 7 rebounds in a 144-140 loss to the Texas Legends. He missed three games in February and March 2020 due to a lower-body injury. Gaddy averaged 12.4 points, 9.0 assists and 3.3 rebounds per game during the 2019-20 season. On July 1, 2020, Gaddy signed with Peristeri of the Greek Basket League.
International career
In 2010, Gaddy was a member of USA Basketball's U18 team in the FIBA Americas tournament. He played a supporting role behind Kyrie Irving. In five games, Gaddy posted averages of 5.0 points and 2.8 assists in 13.4 minutes per game.
