Turner was not drafted to be a backup. He was drafted to be a rotational player. Much easier to do that at DE than at CB. Taylor is a great special teamer that they hope can eventually develop into a nickel guy or contributor in the secondary. I hope he was not drafted as insurance if CGJ negotiations go south.
1st round picks are not meant to be rotational. Cam will be retiring in the next couple of years, so he may slide over to that side but I don't he was drafted to be just a rotational guy.