That's how he usually is in big tournaments. That's how he won the 2012 Olympics and at least 5 of his World Titles. Were you expecting to see a monster coming out and ipponing everybody or something? Dude doesn't always win because his judo is so much better, it's because he's stronger and more athletic than anybody else at HW. And anytime he faces a guy that's athletic and not out of shape, he has some trouble with them. To be completely honest, Riner gets a lot of ref help as well and wins so often by shiido despite the fact that a lot of the shiidos just come out of nowhere for no reason. You saw even in the SF how much trouble he had with Sasson - at the European championships Sasson nearly took him out as well.
If you want to see a once-in-a-lifetime athlete and the best judoka in the world who completely murders everybody he faces, check out Shohei Ono.