Why can't Keith Thurman knock anyone out?
Guys like Thurman and Golovkin stopped knocking guys out once they started to a step up in the competition of fighters they were facing. Thurman got in there with Danny Garcia and Shanw Porter and couldn't get them out of there. Ggg got into the ring with Canelo Alvarez twice and failed to stop him twice let alone even knock him down. GGG had prior faced mediocre opposition. Again it's due to the quality of boxer they're facing.