Josh Rosen, listen up ... if the Cardinals DO draft Kyler Murray tonight, Kurt Warner is handing out some sage advice -- JUST PROVE YOU'RE BETTER!!
"Bottom line is it's just part of it," Warner tells TMZ Sports out in Nashville ... "You gotta go and just prove you're the best guy for the job."
Of course, Arizona drafted Rosen last season thinking he'd be the guy for the franchise's future ... but now, with Kliff Kingsbury at the helm, they're expected to take Murray tonight.
Many have wondered if JR should be upset if the draft pick does go down .