The Dallas Mavericks have agreed to trade guard Tim Hardaway Jr. and three second-round picks to the Detroit Pistons for guard Quentin Grimes, team sources said.Hardaway, 32, averaged 14.4 points in 79 appearances for Dallas last season. The Pistons added the veteran shooter on an expiring deal in order to pick up the three second-rounders.Quentin Grimes has more upside, but the 24-year-old only played in six games last season with Detroit due to a knee issue after being moved by the New York Knicks at the trade deadline. New Pistons president of basketball operations Trajan Langdon said the team wanted to be a dumping ground for unwanted contracts to get assets. This is that.