Former NBA star Charlie Villanueva, who's famously battled Alopecia, ripped Chris Rock for his Oscars barb about the autoimmune disease ... adding that he's "proud" of Will Smith for defending Jada Pinkett Smith.
Villanueva took to Instagram to express his thoughts on the Smith-Rock altercation at Sunday night's Academy Awards ... saying as someone who's had to deal with Alopecia, he knows what Jada is going through.
And, he said he can understand why Smith reacted the way he did following Rock's "balding" G.