It's a good idea and the NBA Players' Association, the union, should cooperate with the commissioner. The National Football League already has a minimum age requirement. No one can play in the NFL until they have been out of high school for three years. In next week's NBA draft, there will be 39 players who still have college eligibility. They include 11 sophomores, one redshirt freshman, four other freshmen, two high school players and nine foreign players under the age of 20.
Money is the driving force.
Under the contract with the union, owners can pay rookies less money for four years. The young players want to get the rookie years over with so they can negotiate for big money. The union has indicated it is amenable to some sort of minimum age. The NFL model is sound. So too is the proposal to extend the rookie wage scale for all those under a specified age.