Talked to Younghoe Koo today about the evolution of his kicking technique and approach angle. Koo, who plays a lot of golf and uses the golf analogies as it relates to kicking, likened his current approach to swinging a wedge vs. the more traditional way being like a 3 wood.
The "traditional" run-up allows kickers to create more rotational force and thus more power into the ball, just like a golf club that is longer and swung from a shallower angle. But Koo found his directional distribution to be much tighter with a straighter run-up, which he admits is probably the most extreme in the league. He also said he sacrifices some power by doing this, but figures that a 60-yard range (indoors) is good enough for what the team needs.
And to add to Sam's point, Koo does indeed work with Carney a bit during offseasons. But he said this re-working was self-taught, and came down to him reverse engineering from the point of contact and finding a way to make that 12-18 inch motion through the ball as consistent as possible.
I did wonder this recently.
I assume it's a John Carney thing, but Carney himself didn;t kick this straight-on iirc.