Before the match starts
When two teams sit down to play each other in a match, there are three key battles :
a) Our Concept versus Their Concept
b) Our Delivery versus Their Delivery
c) Our Luck versus Their Luck
Concept : Bidding system. Bidding style. Bidding philosophy. Play technique. Play understanding. Play psychology. Concept is a theoretical entity.
Delivery : Being able to demonstrate the concept at the table. Mental toughness. Honesty. Integrity. Delivery is a practical entity.
Luck : Finesses. Percentages. The type of hands that come up. Luck is a random entity.
In a vacuum, the team with the better concept should win.
In practice, the team with the better delivery wins.
The closer the two teams are in the concept/delivery spectrum, the higher the role of luck.
After the match is over
Combination of factors above creates a result. The result is a function of the fundamental truth (concept), the peculiarities of the day (delivery) and the randomness of luck.
How valid is the result
The less the element of luck, the more valid the result.
A team that plays badly (low delivery) has no genuine cause for grievance even if their concept is far superior than the other team.