requires them to be in but the range is very broad. So teams that play on very small pitches(fields) often play with a defensive philosophy. If they pack it in, there's too many bodies in a confined space for you to do anything.

Where as Barcelona, for example, plays on a huge pitch and that helps their more offensive philosophy which is passing a million times and trying to hold possession.

I'm a barca fan so I know this happens but it happens to others too but teams will let their grass grow longer when barca comes to play them because it slows down the ball and the speed of hte passes. Slows down the game essentially. Where as the camp nou is like playing on grassy concrete.

The pitch size differences can make a huge diffence in the games because the spacing between players changes and teams that are used to playing really wide with lots of space will be compacted into a small field.

There's also the crowd factor as well which can play a big role.