Apparently, a Reddit user has found the word "momentum" in one of the EA Sports FIFA 17 PC settings files, which contains a set of rules, allowing the game to adjust the difficulty when the player gets too far ahead or behind against their opponent in a FIFA 17 match.
What is the "Momentum"
The word Momentum is a conspiracy theory term given to the methods, scripts and patterns that EA used in FIFA games to control the matches against the players when they are in the lead. EA claimed before that there is no any "Momentum" in FIFA game - This code was not used in FIFA 08 and beyond, but this inline documentation found by a FIFA fan says the opposite.
Where is the Momentum in FIFA 17?
This setting file, which is includes inline documentation can be found and edited on FIFA 17 PC-Windows version and reads as below:
As it documented above, the game difficulty will change if user scores in first 5 minutes, first 20 minutes and/or they are leading by 2 goals.
So, this isn't confirmed that there is Momentum in FIFA 17, but the codes in setting files show that it has been possibly used in FIFA 17 game.