Is Jason Day's lack of hip turn hurting his back?

I watched this video this morning (https://www.youtube.com/watch?v=FaUEI6d76ik), and afterwards compared the swing of Jason Day to Jordan Spieth's, and I can't tell much of a difference in hip rotation.

Is it possible that Day is rotating less simply because his back is bothering him? Or is he purposefully doing it to maintain more control? And is that contributing to his health issues?

Submitted March 30, 2016 at 10:26AM by bl1ndvision http://ift.tt/25woh2w