What is going on with the ranking system?

Over the last 10 games, I've gone from 3489 to 3512 with a 6-4 record. In the same 10 games, my buddy, a mercy main, has gone from 3516 to 3617. He was placed 2300 this season and has been climbing a little faster than me all season, but lately it's just gotten ridiculous. Even in games where I drop 4 golds he'll gain 10-15 more than me. Is there any rhyme or reason to this ranking system?