Hmm...hadn't really thought about it yet. Even with the additional fat and connective tissues of the shoulder, steaks cook quick enough that they don't melt away as much collagen, which helps in lubricating the muscle fibers for a more tender chew. Theoretically, overcooked is overcooked. No matter how you slice it or treat it after cooking you will have mealy/grainy fibers and a drier chew and texture...this is especially true of lean meats. However, with a slow reheating and enough remaining available fat (or added fats) it may come around to a more tender chew. Don't fret, though...you can add the cubed-up meat to green chili or other dishes and actually turn it into a nice treat. Just don't think of it as leftovers...think of it as the base for a new dish. And, nothing beats a smoked meat tossed into an otherwise traditional dish. Just let your imagination run wild, look in your pantry and see what you can toss together...you'll be amazed amazed at the things you can come up with to salvage less desirable cooking results.