First, let me say I am NOT questioning his vocal abilities - he can sing, no doubt.And yes, ballads are his strong suit. Baby I Love Your Way is the only song that ever earned him an encore. He's always been known for his sensitivity.
And he was in a musical theater show, not fronting a rock band.
Yes, his rock qualifications are TOTALLY an issue. No matter what anyone thinks of Marty or JD, no one can honestly question their rock ability.
Navarro thought he could rock (Remember, "You've made us rock, now make us cry"? comment.) I never "felt" MiG myself, but I'll have to accept what they say. But since he switched to the crying part, he doesn't seem to have any edge left at all. Like he went over to the other side.