I still dont think he is able to sell well.
Llorente, Tevez, Coman, Vidal and now Pogba went for too little. There is a few more i have missed.
Coman and Pogba too little? Pogba is a transfer record, what do you expect?
He is hyped up by the media, but he is just a good midfielder for his age. His is nowhere near Pirlo, Xavi, Iniesta, Messi, Ronaldo and (I will get hated for saying this probably) Marchisio yet (for me, Marchisio is the king of our midfield the last two seasons).
Vidal, I agree, I was also surprised, but again, I am afraid this has to do with some personal issues between him and Juve. Tevez really wanted to leave and Juventus allowed him the opportunity. Stupid business wise? Yes, I think so. But I think that Tevez and Juve had such a good relation, they agreed.
Llorente had some high wages and Juve needed some financial space in this section. Probably there was no interest in him whatsoever so they took their loss.
In business, sometimes you make a mistake and you need to take your loss. This is the case with Llorente probably.