HN upvoting can be a mystery sometimes. https://news.ycombinator.com/item?id=6440367
The timing makes all the difference. Luck, too.
The twitter notification part broke at some point (I haven't had time to fix it), but the main chart is surprisingly accurate. It shows that it's been a good time to post for the last hour or so, so this submission was very well timed. That other submission was sent at a particularly poor time (about 2 hours ago), when few people were upvoting on the new page.
Timing really does make a big difference.