I made a chicken soup with large chunks of chicken tenders – all added at the last minute to just poach enough to be cooked but not be overcooked. Maybe fifteen chunks were perfect, cooked through and moist and flavorful, and perhaps ten were amazingly fibrous and tough, almost un-chewable, and basically no good. Since they were all roughly the same size, and had been cooked identically, preparation differences as an explanation went out the window. There is some lousy quality chicken out there.