The margins are that close at this level and Gatland, the Wales coach and a man who led the Lions to their series victory over Australia four years ago, has his qualities.
He is a good coach, clearly. His Lions squad was well prepared across the board, a point acknowledged by his opposite Hansen, but what he hasn't got is "New Zealand experience", the three dreaded words heard by many a work-hunting traveller to these shores.
He hasn't coached here since 2007, and simply put, he's not part of the current set-up, and that in the end may count against him.
The All Blacks' run of success - two World Cups, a Bledisloe Cup, six out of nine Rugby Championships (known as the Tri Nations until 2012) - stemmed largely from New Zealand Rugby's policy to go with continuity, and it would surprise if they went away from that after the 2019 World Cup in Tokyo.
Ian Foster, a coach who has grown hugely as an assistant alongside Hansen, must be considered the favourite, and while Hansen, clearly isn't in a position to have too much sway on his successor, New Zealand Rugby would be silly to dismiss his recommendations.
"All I know there is a massive responsibility that comes with being All Blacks coach," Hansen said today. "I know that when the union in 2007 made the decision after we dropped out of the quarter-final to keep Graham [Henry] and Wayne [Smith] and myself, that that continuity and the fact that we had to take responsibility for that failure made a massive difference to what happened after that.
"Continuity is a good thing otherwise you end up chucking everything out. The formula we've got isn't perfect but it's pretty good, it's been reasonably successful, and having people coming in cold and understanding that makes it harder.
"It doesn't make it not right but I've got every faith in who sits on the panel at the time will make the right decision for New Zealand Rugby."
When the dust settled on this test at Eden Park, one of the most intense and evenly matched in recent memory, and when Gatland put away his red clown nose, he and Hansen had a drink together.
They've thrown barbs at each other for most of the series, as hard-fought as any Lions tour, and they got together afterwards to acknowledge that, although significantly, one will be much happier with the result than the other.
"His and my relationship is fine," Hansen said. "We're not close buddies, only because I don't really know him and he doesn't really know me, but what we do know of each other there is a mutual respect there and when you play a three-test series you're always going to have a yarn."