Johnson has lasted seven years in the NBA but things began trending downward this past season with the L.A. Clippers.
Johnson, 29, had his worst year as a pro, averaging 2.7 points and 2.7 rebounds. Johnson finished on the NBA's All-Rookie Second Team in 2010-11 and owns career averages of 7.5 points and 3.3 rebounds.
While his numbers have dwindled, Johnson's past two Clippers teams have made the NBA playoffs.
Hart lasted nine seasons in the NBA as a backup point guard despite never averaging double-figures in scoring.