The 20-year-old, who is 1.9m "in shoes", scored 26 points to help his former school win its first title by beating the Magic 67-61 in the A grade final last weekend.
So he knew he had had a solid season but, with so many talented players in the league, he thought the coveted award would go to someone else. He was wrong.
"I've never won an award like this before," he said.
"I've never been in any special teams, so it was a great moment for me personally. Especially considering who I was up against - there are some awesome players in A grade."
The Otago Boys' team is mainly made up of old boys and boasts an all-star line-up featuring Otago Nuggets forwards Tom Rowe and Sam King and the likes of Ben Dick and Jordan Small.
Former Nuggets Brent Matehaere and Murray Clarke also suited up at different times during the season.
Being able to play alongside and learn from the likes of Matehaere and Clarke was a valuable experience for Carruthers, who works in retail right now but has some big basketball dreams.
"When people ask me what I'm doing next I tell them I'm going to the [United] States. I'm dead set on going - my mind is made up.
"I want to play college basketball. I'd love to get settled into a junior college over there and just see what happens from there. I've been dreaming about that for ages. Hopefully, I'm going to see it through."
In division two, the St Kilda Bullets beat the St Kilda Dragons 83-80 to win their third consecutive title.
