in his freshman season at butler, mack started in all 32 games, sharing the butler freshman record for games started with teammates ronald nored and future jazz teammate gordon hayward. he was named to the horizon league all-newcomer team and the horizon league all-tournament team after leading the bulldogs in assists in 2008–09, becoming just the third freshman in butler history to record 100 assists. in 32 games, he averaged 11.9 points, 4.4 rebounds, 3.5 assists and 1.1 steals in 30.8 minutes per game. during the off-season, mack helped lead team usa to the gold medal in the 2009 fiba under-19 world championship with averages of 5.9 points per game.