You are right about the silvers when they jump and roll the hook does sometimes come out of the mouth and gets hooked into any part of the fish. Personally I still treat it like a snagged fish and release it. I think the silvers are a good reason why the forward of the gill plate was inducted into the laws. If I could count how many silvers I have hooked in the rivers and have rolled and let the hook go and got them somewhere else. Personally a snagged fish is a snagged fish and would not keep it. If the hook comes out of the mouth then you lost the fish. If it ends up being snagged it is a snagged fish release it my .02