My english is not perfect so I need help to understand the GP distance ajustement speed.

I'm guessing this is just how much you let the AI deviate from your Gameplan.

From my understanding this can change during the game. I honestly always keep it at zero so it wont change so I will always know about what is considered short/medium/long on every down.

This represents what is considered short/medium/long so if you set this high the settings for this distance can change greatly, if its set lower then not as much.

Here is the official explanation:

http://blog.myfootballnow.com/2015/03/short-medium-and-long-what-do-they.html