Height of the player has some effect
meaning that a tall defender or GK or ST playing better
or generally short players have some disadvantage in the game.
Well, that's another MYTH.
The game just takes some numbers from a data bank and giving to players, depending from their position.
GK are usually over 1.90 (and you can have tall guys, good or bad performers either).
Def. some more over 1.80
MC - wingers, have a variety of heights but that doesn't affect their performance.
STs are also tall guys.
A short winger can be a successful header as a tall one. That's more depending from the form of the player or a good corner-specialist.