I think it doesnt affect players individually, for example their stats won't decrease. But I think the overall team performance will suffer if the player playing out of position doesnt suit the new position.
For example oncemore, playing Sol Campbell on the left wing will be bad for your team as everytime you go out wide left, it's likely he'll lose the ball.
I reckon if a player is well suited in terms of skills, height and build for the new position then it would be fine, an idea that playing Papa Bouba Diop at centre back would have no negative effects on the team as he is big, strong, a good tackler and good in the air.
They are my views, goodnight!