Well I wouldn't say that, Pogba was well managed by Allegri, and as his master, he will help him so much to retrieve his best forms. We should see what will happen because from many years ago many thing has been
changed. About defenders I'm totally agree with you, Juventus needs two defender like chiellini and bonucci and we both know that he will not find it easily.
We must not forget that Pogba is not a striker, he is a midfielder. So it is foolish to think that Pogba will score a lot of goals in Juventus and make Juventus' attack very strong. However, Juventus will rely heavily on Pogba's performance next season.
Juventus, on the other hand, must have a stable squad if they want to win the title. If you want to bring continuity of performance, you must strengthen the defense. Because Juventus' defense is weak enough now.