All TMZ Sports had to do was mention Caleb Downs' name to get Michael Irvin fired up -- the Hall of Famer tells us the Cowboys knocked their first-round draft pick outta the park ... and he's gonna help Dallas win a Super Bowl this year!!!

We caught up with No. 88 at LAX fresh off Day 1 of the NFL draft ... and our camera guy only got two words out before Irvin unloaded a passionate rant on the Ohio State standout.

"We're happy about that," Irvin said Friday. "Boy a bad boy, now. That's a bad dude. He is a game changer. He is one of the few right now in the game that plays like that dude Kyle Hamilton from the Ravens. That's the kinda safety -- plays all over the field and makes a difference all over the place. So I'm happy about it."'

The former superstar receiver told us during Super Bowl week he was hoping his old team would focus on defense in the offseason ... and now that they addressed that on Thursday, he said he's even more confident the Cowboys can be in the Big Game this time around.

Irvin also pointed out how Dallas is keeping wideout George Pickens on the franchise tag ... so yeah, things are actually looking pretty good from his point of view.

Throw in his high hopes with his alma mater, Miami, and he's one happy camper.

"Imma have such a great year next year -- Miami gonna win the championship, the Cowboys gonna win a championship. I'm already knowing."