Caleb Johnson auditioned last year and was in a group in Hollywood with James Durbin. He reminds me of David Cook lite. They have similar tones, but David has more finesse while Caleb pushes his voice at times into almost screaming territory. I think he would make a decent middle of the pack contestant, but I would worry the audience might become attached to him and push him farther than he belongs.
Whole Lotta Love cover
Rolling in the Deep cover