"He's a good keeper and I know he can go further and can get better," Stowell told the club's official website. "He's such a willing lad, he wants to learn and wants to work.
"He is dedicated. He's a real workaholic. Sometimes we have to ease him down. It's up to me and the physios and the support staff to monitor him and watch him so we don't over-train him.
"You haven't seen the best of him yet. He's still learning the game. He's only 27 and he still hasn't played enough games to be the finished article."