My son is 12 and hurt his ankle, abs, and back last year during some hard falls. It really slowed him down and couldn't go wake to wake, or any 180's any more. About half way through this summer after encouraging him to keep trying, he got it back and started nailing wake to wakes with grabs again. He still can't do 180's at full speed, but he his building his confidence back.
Bottom line - don't push too hard, but do push a little.
Does he look like he is having fun in this picture?