There's A Better Way To Stop Your Burger From Shrinking In The Pan - Chowhound

When the meat starts cooking, the outer edges lose moisture first. The juices make their way to the center, which causes the patty to puff up and creates unwanted shrinking. By adding that large dent, you're counteracting the puffing and helping hold those juices, and the finished product is a burger patty with little shrinkage. The indent gives the center of the patty room to puff up a little bit and essentially…