The 40-year-old recently shifted back to Sydney fulltime with his family after being based much of the last 10 years in USA, and moved his focus away from Ironman to the half distance of Ironman 70.3 in the burgeoning Asia Pacific region.
"I always considered 70.3 to be my best distance. But once you are doing Ironman in Hawaii as the main focus, it basically dominates the year," Alexander said.
He said that his growing family of three needed to come first and be settled back in Sydney.
"I am excited for them and I am excited to focus on 70.3 and the Asia Pacific region."
Alexander is thrilled to be racing in Auckland.
"I have heard the course in Auckland is challenging and spectacular, with the athletes having to ride over the harbour bridge.
"I am hopeful my form for the race will be very good. Apart from being a much earlier start to my season than normal, I have trained well but I started back to training much earlier than I normally would to prepare."
Frodeno (Germany) won the Olympic gold medal at Beijing and was sixth in London, chalking up three wins and 11 podiums before moving to the endurance distance, where he finished second in the Ironman 70.3 European Championship in 2013.
Now based in Australia with wife Emma Snowsill, Frodeno has also had experience on the Auckland waterfront in the ITU World Triathlon event last year.
The 30-strong final men's field is a virtual who's who of the Ironman world, including 18 winners from Ironman 70.3 races last year, nearly one-third of all worldwide events over the distance, and 40 podium placegetters.
Bozzone leads the way with four 70.3 wins last year, Alexander had three, Docherty, Kemp, two-time Olympian Courtney Atkinson and fellow Australian Ritchie Cunningham two each. The other winners from 2013 in the field include super-talented Tim Reed, and high-flying fellow Australian young guns Sam Appleton and James Hodge, who was fifth in Auckland last year.
The race will also be a homecoming for former Aucklander Paul Amey, who has competed in Great Britain colours for more than a decade.