It would have been tough on the 31-year-old, who has taken a back seat to Jerome Kaino and even Victor Vito more recently. He has been tireless as a leader at the Chiefs and was last year neck and neck with Kaino in the running for the No 6 jersey.
"You get a bit nervous when you haven't had many opportunities but I've had four years to stake a claim and I've worked my arse off to get here," he said.
"It's been a four-year struggle but I'm really pleased and excited to be here.
"I'm excited about the opportunity of going to the World Cup but then I also feel for the boys who missed out. I know they will be hurting and I know exactly what they will be going through. I'm sure those boys will keep their heads up and keep working hard."
Messam said of the anxiety which began to creep into the group as the weeks ticked by before the announcement: "We try our best to block it out and focus on week-in, week-out. In the last test against the Aussies we really just focused on that one game and you could see the damage these boys can do."
The selection of six loose forwards - Messam, Vito, Kaino, Richie McCaw, Sam Cane and Kieran Read - allows the All Blacks to cover what Hansen described as a heavy workload area, but it also gives them mobility on the reserves bench should they decide not to have specialist lock cover there.
The All Blacks want to play the game at pace, that desire is obvious.
"We can cover that fourth locking position with JK [Kaino]," Hansen said. "We've got quality lineout jumpers in Victor and Kieran Read so it does give us an opportunity to put two loosies on the bench, which gives us versatility, helps us with how we want to play late in the game.
"We've two world-class locks in Brodie Retallick and Sam Whitelock and Luke Romano's not too far behind them either."