A collegiate All-American at Oregon, Ballard averaged 12.4 points and 6.1 rebounds over an eleven-season NBA career with the Washington Bullets, Golden State Warriors and briefly, the Seattle SuperSonics.

[5][6] Ballard set Oregon's single-game scoring record of 43 points, in a National Invitation Tournament game against Oral Roberts University on March 9, 1977.

As a rookie in 1977–1978, Ballard averaged 4.9 points and 3.5 rebounds in 76 games as a key reserve for Coach Dick Motta, playing beside Naismith Basketball Hall of Fame inductees Wes Unseld and Elvin Hayes, along with Mitch Kupchak, Phil Chenier Bob Dandridge and Kevin Grevey.

The Bullets defeated the New Jersey Nets 2–0 in the Eastern Conference playoffs before losing to the Boston Celtics with Larry Bird, Kevin McHale and Robert Parish 4–1.

[13] Playing on the front line with Jeff Ruland and Rick Mahorn in 1982–1983, Ballard averaged 18.0 points, 6.5 rebounds, 3.4 assists and 1.7 steals, as the Bullets finished 42–40, missing the playoffs.

[18] Ballard then averaged 7.9 points, 4.8 rebounds and 1.2 assists in two seasons with Golden State and Coach George Karl as a key reserve, playing with Sleepy Floyd, Joe Barry Carroll, Chris Mullin and Terry Teagle.

[21] Ballard worked a total of 21 seasons as an assistant coach and a scout for a number of franchises, including the Atlanta Hawks, Minnesota Timberwolves and Dallas Mavericks.

Ballard was survived by his wife Donna, and their children, Lawrence, Gabrielle and Gregory Jr.[22][6] “I would say this about Greg Ballard – and you can ask any question you want but my opening statement would be – for a guy who played in the league for 10 years and was a good player, I found him to be one of the most humble people I have ever met in my life,” said Gary Schmidt, a colleague as a scout for the Boston Celtics.