Sorry, but this has home sick written all over it.
Why leave now? He was 2A/2B with Ameer, heading into his sophomore season. After one more season, he'd have every chance to be the clear cut number one back. He would've had solid reps this season, and two more seasons as a potential every-down back.
If he wants more playing time, sitting a year for a transfer doesn't make sense. Green didn't even want to red shirt.