Funnily enough I emailed aphyr earlier this afternoon to let him know that the current submission was at #1 on HN and that https://news.ycombinator.com/item?id=23285249 had strangely failed to make the front page despite all the upvotes it got. There wasn't any moderation in either case. Nothing has changed recently. There's just a lot more randomness than people assume...2000 submissions a day competing for the same 30 slots creates a lot of weird high-pressure effects.