Why did I spin a main bearing?

Well now im really confused. i inspected all main and rod bearings and everything looks fine. i took apart the oil pump and the chunk definately went through and caused a little damage (pic). all the cam bearings look questionable and the cam feels "sticky". i plan on getting them replaced by someone that knows what theyre doing. i could not budge the cam with the rockers on. also the cam drifts back and forth about 1/2 inch. this seems like a lot. is it possible the cam moved forward and it skipped a few teeth on the oil shaft? the teeth look a little wierd in one spot (pic). Im really confused on how it lost oil pressure and didnt run since and where did the chunk come from? Im getting a little frustrated still chasing this mystery issue. any help is greatly appreciated