One of the main discussion points on these forums has been the Vikings defence this year.
Defence boils down to trust.
If players trust the system that the coach puts in place, and they trust each other, and the system is a sound one, then the only way that a team can break that down is when individuals within the defensive structure make mistakes.
This happens all the time, it's just basic human nature to make mistakes, especially when under pressure. Fatigue also comes into play when defending, as the more tired you get, the less alert you become and when things happen quickly, which they do at the top level of the game, it's hard for tired players to react.
So I suppose you could say that maybe they aren't as fit as they possibly could be.
But then again, when you are coming up ball and giving penalties away, and find yourself on the back foot for 60 minutes of the game, it's inevitable that you'll get tired.
Are their trust issues in the squad, amongst players? Do the players trust the coach? Do the players trust the defensive system in place?
Unfortunately, working hard and having desire isn't quite enough, especially when you are playing against some fantastic attacking threats and in all honesty, when some of the players in the defensive system are very average.
Good teams are able to highlited weaknesses in the defensive line and exploit that.
Can Denis replace the weaknesses with better players? See my previous post