Well I think the fabric quality has deteriorated continuously season after season with Dior, the more often I checked back, I saw less of the nice British or Japanese wools and more of the mediocre qualities that brands like Prada or Boss would use in their collections. I think that's a fatal mistake for a 'minimal' product as that, you better have it all made in flawless fabrication. It's also best to keep in mind that the petite taille sizing does not work well on a variety of bodies, it's the men's cut, adapted to female standards, with slightly smaller volumes in the shoulder and the arm, sometiems the length of the jacket. It will most definitely not make you an amazingly small waist, but that's probably not the intention there, if you go for a properly 'mannish' suit jacket.
I don't know if they changed fabrication at Dior when you bought your suit, but they used to work with one of the leading producers in Italy for men's RTW suiting when the label got started, I saw similar decline starting in S/S 2006 with the shoulder pads or arms not being correctly inserted by hand, so that you would see odds and ends of the pads poking out from the shoulder... eeek!
Back to Balenciaga, though.
I think the jackets they were showing on the mannequin were indeed production pieces as they were regularly labeled and since I saw more of these styles hanging on the racks...
I think generally we are coming to a point in high fashion where it's about time to separate who is running a house with a true artisanal background in clothes making or if it is one with an emphasize on offering a global luxury goods vision and distribution. At a scale as Balenciaga and all the major houses are aiming, with higher quantities and sourced-out manufacturing contracts, you cannot deliver the same level of quality as if you were working with smaller ateliers and small production runs. I think at Balenciaga you can actually have some pieces made to order or buy some of the show pieces of the rack that are hand-made in Paris, such as the Lesage-beaded pieces and some of the elaborately-cutted jackets and dresses - S/S 2006's riding jackets with lace panels and corsetry boning were for instance made there, and it obviously showed in the price tag, not taking into the obvious effort of the making.
It's interesting to see a label like Boudicca slowly growing into a more classicist, demi-couture direction with genuinely hand-finished pieces. As some might already know, they have always been well known for their (sometimes deconstructed) men's tailoring and exquisite fabric choice. I find their's to be truely worthy investment pieces season after season, judging from the level of debth they put into the making of their clothes - It's sometimes for the sake of accessorization and showmanship that their look appears difficult from first look.