Early in preseason Robinson spoke of working on different formations, including 3 at the back. Long, Moore and Thorniley give that option, especially with Gorrin's athleticism ahead of them. I'm not normally a fan of a back three, as it often becomes a back five with wing backs sitting in and leaves a weakened midfield. But the likes of Williams, Whyte and Holland are hardworking wingers who can track back too.
Imagine a line up of,
Stevens
Long Moore Thorniley
Gorrin
Whyte Brannagan McGuane Holland
Taylor Winnall