Years ago I struggled with a product molded in nylon, and though we received it in 25 kilo bags, closer inspection revealed that almost 25% of the bags had been punctured and re-taped upstream by either the shippers or our own material handlers. As you know, it doesn't take much exposure to moisture for this material to get too "wet" to process. I dried everything, even right from the bag. Punctured bags received from our supplier were rejected and returned. Also, it was a requirement to load the whole bag into a dryer. No open bags were ever saved. And at the end of a run any remaining material was discarded if it remained in the dryer more than 4 hours after stopping the press. "Overcooking" this resin will degrade it rapidly.
In injection molding, for any faults error on any 3M (Material, Machinery/Molding variables, Mold) maybe responsible. If you have earlier used similar combination of material & got satisfactory results (Reference sample may be available), then compare MFI values of base resins, if the values are same, then grade may differ & you have to get characterization results ( DSc/TGA) to ensure same combination being used.
For satisfaction, you may test MFI, density of raw material (Resins) used for product molding to compare with old raw material specs. Chemistry wise, materials molecular weight may differ (MFI will change) or MWD (molecular weight distribution) may not same as old stock. If you are getting compounded PC+ABS blend from compounder, then percentage of individual resin components (PC & ABS) may vary or they might have used different grades of PC & ABS in preparation of blend.