I will disagree with this. Sampras' BH was just about adequate (and less than that, on slow courts / clay), whereas Becker's backhand had a tendency to break under pressure.Agassi weakness? Volleys
Djoker weaknesses? Volleys and overheads
Edberg weakness? Forehand
Connors weakness: Low forehands
I see absolutely no weaknesses in the games of Sampras, Becker, McEnroe, Lendl or Fed, aside from mental strength issues with Lendl and Roger. If you want to address mental weakness specifically, that's another topic and another thread. Conditioning among ATG's also could be addressed.
As I mentioned above in the thread, Becker's BH was a lot more suspect than Edberg's FH. While not a dominant shot, Edberg was not missing much on this side.