One detail we (or I) don't know yet is when the 'cap' is applied. I assume it's per player.
Suppose a 75K player beats a 20K player and a 40K player, according to the math he gains (80 - 110) + (80 - 70) = - 20.
If it's capped afterwards he simply gets nothing or 2 points for beating 2 players.
Yet I assume it's capped per exchange and he should earn 1 + 10 = 11 points.
It must be the latter or the totals would get screwed up, I doubt the 20K player would gain (-80 + 110) = 30 points for losing from the 75K player.
It must be capped at minimum 1, maximum 160 for each exchange between 2 players to make sense. However bugs are always possible (and likely since in the beginning you could have your DR reset upwards for losing SR...)
Another possibility is a disconnect that did not look like a disconnect to you. The server registered a disconnect before the online save, or maybe the online save failed, making the server believe you disconnected. Meanwhile you get back in the lobby screen with the wrong information on the screen. I've seen this happen before with negative time splits displaying from people getting disconnected after the finish. And the game has also kept me going for a while when my internet was definitely already out... A glitch can always happen.
I've been everywhere on the spectrum as well and while
@jasguer's site was still active it logged every DR change for every race and it all checked out, including the borked DR upwards reset. Over 6000 races, 480 wins, I've not yet encountered losing points for winning.
We need more data!