Understanding the tenderness or toughness of beef cuts starts with a simple observation: the more a muscle is used during an animal's life, the tougher it tends to be. The less it's used, the more tender it is.
A helpful way to determine the potential tenderness of a beef cut is by considering its proximity to the center upper back of the animal. Central cuts from the rib and loin region are typically more tender. Conversely, as one moves away from this center—say, towards the front brisket and lower flank—the cuts become increasingly tough.
To visualize this concept, think of the beef rib area. The muscles here do little work other than supporting the animal's breathing, which is light exertion compared to the constant ground-bearing force on leg muscles. This is why cuts from the rib area, like ribeye and Delmonico steaks, are so tender and sought-after.
In contrast, the leg and shoulder muscles, such as those in the shank and plate region, are responsible for the locomotion of an animal that weighs over 1000 pounds—they’re bound to be tougher because they’re made to work harder.
This principle also applies to other meats such as pork, poultry, and lamb cuts. In each case, the muscles that are used the least yield the most tender cuts, while the most exercised muscles yield the toughest.