"The week before we'd beaten Gold Coast 42-0 and were very confident of making the finals but we just didn't play well and ended up finishing ninth."
Tomkins played only 13 matches in 2015 due a knee injury, scoring just once in a disastrous campaign that saw the Warriors lose their final eight matches and slump to a 13th-placed finish.
Kiwi fullback Roger Tuivasa-Sheck was then signed from the Sydney Roosters putting Tomkins' place under threat and he jumped at the opportunity to return home.
"That second year was tough, I am not going to lie, I was sick of being injured and not being able to play and help the team," he said.
"My son was then born so it was the right time to come home, and be closer to family."
Despite his struggles, Tomkins is far from bitter about his experience in New Zealand.
"I loved my time there, the Warriors are a fantastic club," he said. "I made some friends for life and the chance to play with top-class players like Shaun Johnson every day in training was great.
"But coming back home to Wigan felt right. The club hadn't changed much from when I left and I've slotted straight back in."
Tomkins will miss Sunday's World Club Series showdown with Cronulla due to a longstanding foot injury that sidelined him for the Four Nations and Wigan's grand final success.
"I was gutted to miss the Four Nations, and the grand final" he said. "I'd have loved to have played this game against Cronulla in front of our fans but hopefully I'll be back out there soon."