regarding Terunofuji:
i think it was one of the first bashos of 2016 where he still looked like the next big thing but picked up an injury and didn't take enough time to recover.
he dropped out but immediately entered the next basho where you could see that he's not fully healed.
this is where it all started to go downhill and what where seeing now all dates back to that.
it's either retire or a really long time off and restart from the bottom for him.
Osunaarashi's case is similar i think, talented guy but constant injurys will shorten his career.
interesting article:
https://www.japantimes.co.jp/sports/2017/11/01/sumo/sumo-needs-tackle-cause-rising-injuries/
"One of the problems with determining the level and extent of injury in sumo is getting accurate information. Athletes are under no obligation to provide it and the old ‘tape it up and keep going’ attitude is still prevalent."