OP.GG MMR Tracker

So, I'm currently in GOLD 3 and I've been winning a majority of my games and I'm in placements atm. I was following my MMR Via, OP.GG and it said 3 games ago that I was 1627, I won three and its dropped me down to 1,584. How is this even possible?

Yes yes, I know this is a 3rd party website and riot has no control over it. I'm just wondering if anyone else has experienced this or knows whats going on.