John Salley Adamant Chauncey Billups Is Innocent, '100 Percent' Framed

John Salley is certain Chauncey Billups didn't help rig card games to make the mob money ... saying this week he's "100 percent" sure his good friend was framed.

The NBA legend didn't make many bones about it during an airport chat on Thursday ... insisting there's just no way the suspended Portland Trail Blazers head coach knew of any kind of illegal activity at poker games he attended.

"You think Chauncey's got time to make [an X-ray] table?" Salley said. "Like, 'Hmm, we're going to make this table and we're going to go --?' No."

"He flies into Vegas," Salley continued, "they pay him to use his name, he's playing poker. He gets paid to play poker."

"You'll see."

Billups was arrested last week after federal prosecutors claimed he was in cahoots with mafia families who swindled people out of millions of dollars by luring them to play in rigged poker games.

The feds alleged Billups was used as a "Face Card" who would draw "fish" to the table ... before his co-conspirators would deploy high-tech equipment to ensure the victims would lose.

Billups' attorney has refuted the allegations -- and Salley made it clear he believes the Hall of Famer's denial.