Ok.. well first of all i think GL put 12 parsecs in the script because it sounded cool..
None the less. In an interview with him GL that i once saw, he tried to explain that when the millenium falcon did the Kessel Run in less than 12 parsecs Han Solo was actually refering the the speed of the hyperdrive computer which computed all the different jumps to get from point A to point B.
I belive what he was trying to say was that other computers were slower and not as accurate. Hence their jumps needed larger margins for error and thus did longer jumps. The ME on the other hand was more precise and take more short-cuts.
So the red arrow would be the ME, while the other (green and blue) are other ships.