Mills is a good bowler but you can't compare them with quality of Pakistani bowler even at the moment You can't compare the with any of the world's team even not with Australia.
They have strongest seaming as well as spinning line up.
Vettori is a very good left arm spinner but what about variety?
Ajmal and afridi has lot which will urge team selector to choose them.
I dont' get why you guys think Pakistan has such a quality bowling line up. I agree with you that on their day they are great, but they are just so inconsistent. No way they have the strongest seam and spin attack.
Re: Vettori, he probably has close to the most amount of variations in world cricket, he varies his pace, spin, flight etc. and changes it up every ball. That is why he is such a great bowler as he is not a great turner of the ball.