However, I personally would be much more interested in any info on how he got the word out and attracted users. That's the part most developers are missing in the "that makes money" portion of the equation.
One of the biggest sources of traffic for me now are the Rocket League analysis / training subreddits[10]. It's become _the_ location to upload your replays if you want to share them with other people. Making it easy to share (no account required) was a big part of this.
[1]: https://www.reddit.com/r/RocketLeague/comments/3et5yx/after_...
[2]: https://www.reddit.com/r/RocketLeague/comments/4f3jq2/rocket...
[3]: https://www.reddit.com/r/RocketLeague/comments/4d1kpe/rocket...
[4]: https://www.reddit.com/r/RocketLeague/comments/4a9s44/rocket...
[5]: https://www.reddit.com/r/RocketLeague/comments/44xp8j/rocket...
[6]: https://www.reddit.com/r/RocketLeague/comments/3yws8d/rocket...
[7]: https://www.reddit.com/r/RocketLeague/comments/3pra3u/rocket...
[8]: https://www.reddit.com/r/RocketLeague/comments/3gtulm/rocket...
There's a user in the Heroes of the Storm (Blizzard moba, same engine as SC2) that did the same thing, except went the completely opposite route and riddled the site with predatory ads (the kinds that produce popunders and play audio on load). The paid option was to get rid of the ads. Most updates to the site lately seem to be to combat ad blockers instead of add new things.
The community went from being extremely open and excited about the site at the beginning to now begrudgingly having to use it since it has no competitor.
Props to you for engaging the community and keeping them on your side.
(Also, thanks!)