Melodyne Studio is an incredibly deep program, but it can't do everything. Pros may use its many tools right down to syllable levels. But unless it's something really out of whack I'm probably going to just use the slider at about 85% instead of spending a couple of hours.
Hoarse, breathy vocals can have density added using clippers like Karzog's KClip to increase RMS energy and also using super heavy paralleled compression with something like a Fairchild plugin.
It's recommended to tune first, but there is no harm in experimenting.
And Willie proves that the most compelling thing is performance. If there is no feeling, nothing will make it sound great.