Its crossing the external barriers and instilling flavor. When you cross the barrier of the external outside edge of the meat you got the flavor inside the bag. Meat is encased in membranes that serve to keep foreign objects out and clean systems in. These membranes, fat layers, are hard to cross.
When you inject you get flavor content right in the moisture of the meat. Butcher BBQ said you will never get injection inside the muscle striations. I don’t believe it. The striations are like gelatin. The proteins hold water which gives the muscle a reaction medium in which to act. Calcium goes in and potassium comes out as the muscle contracts and relaxes. This fluid has a membrane around it that is made primarily of Cholesterol. Our bodies need cholesterol as a building block for our bodies.
When they produced Simvastatin a medication for Cholesterol reduction they were trying to stop a cycle that creates Cholesterol. They tried the wrong place in the cycle and the animal they tried it on basically fell apart. We need Cholesterol to hold our cells and organs together.
All the Proteins, Cholesterol, and organic matter made up in a hog, chicken, or beef is non-polar. That means salt containing polar materials are repelled by them. Soaking a piece of meat will never do what injecting will in combination. Having said that, soaking is very effective in enhancing flavor. Injecting will finish the deal. When you inject the injection goes between the fibers of meat.
Myron Mixon’s crew told me he injected Hams until they were big as basketballs. The more injection you can put in the more flavor is going to stay in there. A lot of the fluid will evaporate but the flavor mix is going to stay inside the meat, inside the bag that is covered in membranes. Inject till your hearts contest. Brine for 12 hours then inject. It will double your flavor. Then rub, smoke, rub, wrap, smoke, sauce, and cut to serving! That is a formula for success.