Sherratt pointed to Winnett's workload over the past 12 months.
“Because he was moving around from week to week, even though he wasn't hurt, he was having some discomfort,” Sherratt said.
“I think he played 27 games last year. The year before that, he had about a dozen mixed appearances for Cardiff RFC, a couple for us and some Wales Under-20s.
“So his development in the short term has been absolutely tremendous.
“It's been a tremendous straight streak, from Cardiff, to a couple of provincial games, pretty much starting every game for Wales and playing very well.”
