If he's eating it, then thats bad. You need to correct this. Reteach "hold" use freshly killed birds if possible, if he attempts to eat, slap his snout with your hand or pinch his ear, ecollar correction, etc.

Him not going hard at the birds is you not correcting him for not doing that, you have to nick him if he doesnt get turned and going hard at the back pile. He will soon learn that he needs to try to beat your nick and he will speed up.