Just as there are swing states in the United States election, so too are there players whose form will have a significant bearing on the make-up of the All Blacks squad for the Wales tour to be announced at the end of this month.
One of those swing players is Blues lock Patrick Tuipulotu, who will be closely monitored over the next few weeks for reassurance that he's returning to being the athlete he was before suffering serious injury in 2015.
Tuipulotu is a swing selection because, if he's included in the All Blacks squad at lock, it will affect who is picked as a loose forward.
By the end of 2014, Tuipulotu had established himself as a regular bench All Black. Coach Steve Hansen liked Tuipulotu's ball-carrying power and ability to charge up the middle and take the All Blacks over the gainline.
At 1.98m and 125kg, Tuipulotu is a big presence with the explosive power to make an impact in test football. He and Blues team-mate Charlie Faumuina were strong All Blacks bench cards that year, being thrown into the fray to get over the top of defences and sap them some more.
When Tuipulotu was ruled out of the World Cup due to his need to have two bouts of hip surgery, they never quite felt the same about the portfolio of his replacement, Luke Romano.
The Crusaders lock plays in much the same way but at the World Cup the All Blacks were content to play the knockout rounds without a specialist lock on the bench.
They took a calculated risk of having two loose forwards as back-up, which was partly because they felt the tackled ball was a more influential facet than the set-piece and partly because they didn't feel Romano offered quite enough athleticism and agility.
They have a different view of Tuipulotu, though.
If he can return to being the same athlete he was at the end of 2014, the All Blacks would like to use him in the same capacity - coming off the bench to hammer defences.
When he's in prime condition, Tuipulotu is nearly as mobile as a loose forward and can contribute around the tackled ball.
The selectors feel they have the best of both worlds with him.
And because of that, they will look quite differently at their loose forward reserves, given probably only one is going to be needed on the bench.
Whether a loose forward can cover lock if needs be becomes of less importance if Tuipulotu can prove he's ready to return.
It wouldn't be a surprise to see Elliot Dixon, Liam Squire and Ardie Savea picked at loose forward, alongside Jerome Kaino, Sam Cane and Kieran Read.
If Tuipulotu doesn't convince the selectors he's still the same athlete, then someone such as Steven Luatua, who can cover lock, may come more into their thinking.