Jennings was awesome for us defensively when parked alongside Moses, but it shouldn't be forgotten that he doesn't get near the time or room to make those decisions if the second rower inside Moses is f**king it up, and getting his edge outnumbered. Whilst Hayne hasn't shown the quality of Jennings decision making in defence in the time he has spent at centre, I'd reckon he's not that far behind, and the guys inside Moses will be the same, 'cept with another season of experience under their belt.
So I don't see Hayne defending on the right at centre and moving Jennings to the left as problematic.