I was excited for the idea of Rainmaker, and I did enjoy playing it. My ranking, however, did not. It's probably because Rainmaker emphasizes teamwork more than any of the other modes, and randoms are unreliable.
Anyway, after long losing bouts in ranked, I recover from the lost rating by waiting for Splat Zones on stages I like, since I can push victories more easily on those. In the meantime, I play Turf War amid the salty tears of my lost points. I went from A+ 96 to A+ 7 on a bad run of Tower Control once, and was able to push to S that day by doing this.