I'm thoroughly confused by the way points work in Hero League. Based on my experience with the game, I think there's 300 points in each rank. I often run into this scenario: I'll be a certain rank with less than 100 points. I'll lose a game and get -100. But instead of going from rank X with 50 points to rank Y with 250 points, I go to rank Y with 150 points. Can anyone offer insight into why it works like this?
They have separate borders for increasing in rank and decreasing. So you need more points to gain the next rank than you need to hold the rank once you have it.
If there were a single barrier between ranks, then people at the border who win 50% of their games would be constantly going up and down in ranks. This way, a single loss against an equal or better opponent shouldn't cause you to drop in rank. You have a little margin.
Of course, if you gain a rank after winning a match and lose the next two, you'll still drop back down. This sounds like the scenario that you are describing. But if you are gaining and losing about the same amount of points each time, you should be able to weather a single loss right after gaining a rank.
And of course, if you are losing more points on a loss than you gain on a win, then anything goes. But that should be rare as it means that you are getting matched against weaker (in MMR) opponents without consistently winning.