Marinades do flavor the meat. But contrary to popular belief, they only do their wonders on the surface up to a few millimetres (4 mm max) into the meat.
Meat Science: Does Marinating For Flavor Really Work?
How Do Fruit Enzymes Tenderize Meat?
In preparing meat, the food is tenderized for easy cooking because the collagen in the meat makes it tough to digest. Collagen is the most abundant protein in meat. But tenderizing break down the meat fibers, making the meat easier