我找到你说的理论根据了， 你说的是对的

Do I cook a beef roast fat side up or down?

In most cases, you should cook a rump roast with the fat side up. As the roast cooks, the fat melts and runs down the sides of the meat to baste it and provide flavor and moisture. If the fat is sitting on the bottom of the pan, you won't get the same benefit.

 

老公网上查的， 是骨头向上