First off, we have a midfielder already on our squad who is better than him, and that is Pogba. Vidal is a terrible passer, and can be a liability when things aren't going well for him. That "warrior spirit" is a blessing and a curse
But because Pogba A) IS not a drunk B) Is not a "bad Boy" and C) is actually coveted by the top teams in the world, you don't rate him nearly as high as you should