Casley came back from a serious shoulder injury to slam a three-run home run in the world championships final against Venezuela in Auckland in March.
After leading the Black Sox to a record sixth world title, Casley expressed his desire to play through to the next world championship tournament in Canada in 2015.
He played at last month’s International Softball Congress tournament in the United States for the New York Gremlins, but the 34-year-old has now been forced to call “time” on his long international career.
Casley, a Hutt Valley builder, told Sportal.co.nz that four knee operations, a fractured vertebrae and ongoing shoulder injuries had taken their toll. He wrote a letter to his teammates to tell them he had decided to hang up his cleats.
“This is not something I have taken lightly. The Black Sox have been the biggest part of my life for 14 years. My heart is still very much with the team, but my body is telling me enough,” he said.
Casley said telling new Black Sox coach Mark Sorenson he was retiring was one of the hardest things he had ever done.
Sorenson told Sportal Casley was “a strong leader and was in integral part of our plan in having continuity in leadership.”
“It’s a shame because he still had a lot to offer the game,” he said.
The Black Sox have only had five world championship captains in the last 30 years _ the late Kevin Herlihy, Carl Gould, Sorenson (three times), Jarrad Martin (twice) and Casley, who took over in 2010.
Sorenson said they had two years to “work around a new captain” and he would consult his coaching predecessor Eddie Kohlhase before making a new appointment.
Within the current squad, veteran infielders Nathan Nukunuku and Brad Rona and outfielders Donny Hale, Ben Enoka and Daniel Milne, have leadership experience.