I'm not so sure that the drop off in the stats is down to fatigue. To me it seems that already, other teams are playing in a similar way. So they are countering our style and imposing themselves at the same time.
If you look at how the German teams dominated the Spanish in the Euro semis, it appears that the game has already moved on a notch. They are able to mix up the pressing/keep possession style but at the same time utilising a modern take on the 60's style game with quick wingers and longer passing when appropriate.
We have the plan A game working well, we now need the plan B that enables us to get more sped and penetration into our attacks.