Ideally when characters spar, are there rare instances that certain characters who lose to others frequently manage to win?

[WingZeroRequiem]

I know it doesn't apply to the tournament but I know for instance that if characters who frequently lose to a character spar end up winning with a 50% chance even through improvement. It takes many losses of characters just to beat a character in the pre-DOA tourney and once they enter the tourney do they lose for real. What are such cases? Do you realize that powerful characters are not that strong at all?