Have you ever seen a team coming to the game trying to defend their title? They have that title. And they also have to waste energy to defend it. A portion of their energy will be drained by fear of loosing what they have.
And since they are not only trying to win - but also trying to protect and defend what they have - they are less likely to succeed.
The opposite is also true. Having nothing can make you stronger. You have nothing to loose. And can use all focus and energy forward - to win.
(Beware. If you in the game suddenly think you have won already, you will spend time defending something you think you have...)
This is why the underdog is stronger. He has less to defend. And can only win.
So, what we normally think is good - "having something" - can be a bad thing. And what we normally think is bad "having nothing" can be good.
Oversimplified of course. But the patterns are there. In sports and in business. And in love!
If you have a lot of defend it will be harder to be offensive.