If LiAngelo Ball were coming out of college this year, he'd be the No. 1 overall pick ... AHEAD of Zion Williamson -- so says LaVar Ball, who tells TMZ Sports, "He can't hold a candle" to Gelo.
"He ain't no big baller," LaVar says of the Duke superstar ... "He's a Williamson. Williamsons ain't stronger than Ballers!"
Of course, Gelo ain't available for this year's NBA Draft ... he already had his shot to be taken in 2018 -- but wasn't picked with any of the 60 selections.
But, the Big Baller says his middle son has gotten SO much better in the last year ... he tells us Gelo would be a surefire bet to be selected over Zion if he were eligible this June.
"Biggest and the strongest 2-guard in the NBA right now. Ain't nobody built like him at the 2-guard. Nobody. 6-6, 240, can shoot the 3, post you up -- kill you. But, you going to see. You going to see."
In fact ... LaVar is so confident LiAngelo has upped his game -- he's PROMISING his son will have an NBA deal by the end of 2019.
"I guarantee he'll be in the summer league, and guarantee he'll have an NBA contract this year. How's that?!"