Ball -- along with Master P and Metta World Peace -- joined the guys from the office for "TMZ Roundtable" ... where they talked about everything from getting their sons to the NBA, to how basketball has helped build their businesses off the court.

Of course, all the guys have kids who are rising hoop stars -- and all 3 men have made radically different decisions on how to get their sons to the pro level.

LaVar says he not only stands by his decisions to take LaMelo Ball out of high school in the United States (he went to Lithuania and Australia) ... but says he's convinced Melo will be the #1 overall pick in the 2020 NBA Draft.

Ball says his dream would be for the NY Knicks to hire Mark Jackson as the next head coach -- who would then take Melo with their first pick.

In fact, Ball says he sees a world in which all 3 of his sons sign with the Knicks and play in Madison Square Garden. He thinks his fam can save the franchise.

Metta World Peace says Ball's youngest son is the real deal -- and thinks he'll be a force to be reckoned with at the top levels.

As for Master P, his 2 sons are rising up the ranks too -- but P says even if his kids don't make it to the NBA, he's setting them up for success in the business world. You gotta hear his plans.