"I can't see how the deflectors did anything at all to help with the initial impact "
I don't think those are wire deflectors. They look more like supports for the weight of that overhanging intake filtery stuff. Besides, any wire hitting them would ride up and over them and catch in that rather nice trap just below the "duck hatch". Also the front of the cab has too many other unprotected wire catchers, e.g. the windscreen wiper posts.