Eric Dickerson is convinced Ezekiel Elliott is innocent -- and says the NFL overstepped by punishing the Dallas Cowboys star after prosecutors declined to press charges in his domestic violence case

The NFL Hall of Famer didn't mince words at the Malibu Chili Cook-Off this weekend when talking about the situation to TMZ Sports -- "I think they shoulda stayed out of it. The NFL should have stayed out of it."

Dickerson says if Zeke DID physically abuse his girlfriend, the punishment is still too harsh -- he feels a 3-game suspension would have been more appropriate. 

But the bigger issue ... Dickerson says he doesn't think Zeke committed a crime or did ANYTHING warranting a punishment. 

And if the law doesn't punish a player, neither should the NFL.