Lets say that you are 990/1000 points until your next level up. You then win your next match, in which you'd usually get 30 points give or take. Instead it only gives you 10 battle points you need to level up, and starts your new level with an empty bar. It's happened to me mid-tourney a couple times, and is annoying when up there with the leaders.
Winning three of the four rounds, assuming no penalty cards, should get more than 30 points at least. How much higher depends on the exact circumstances, of course. Never should it give 24 points, even in the new scoring system. Not in my experience, anyway.