I think if the right MLB falls to the Broncos they will take him, but that's a big if. As for DJ playing MLB, I guess I'll trust the Broncos to make that decision. My understanding is that the last time DJ tried MLB he failed because he couldn't grasp the playbook, not because he can't tackle or shed blocks or flow or whatever.
As for Irving, I'd love for this guy to pan out. He's definitely got the most upside.
As for Johnson, love this guy. He's got fantastic instincts, he's always around the ball. He is a true LBer at heart. That being said, dude is just not very fast. Now, if he's always in position due to his instincts and correct reads, great! But if he missjudges a play or takes a bad angle, seeyah! He's gonna be way behind.