demotion from ōzeki ranking
Sumo term: when an ōzeki wrestler loses the rank due to poor performance, typically after consecutive losing tournaments.
See also: 大関 (おおぜき)
If the ōzeki who had a losing record last tournament also has a losing record this tournament, he will be demoted from ōzeki.
大関 is the second-highest sumo rank; 大関陥落 is the event of losing that rank.
陥落 means 'fall' or 'surrender' in general, but in sumo it specifically refers to demotion from a rank.
Compound of 大関 (ōzeki, the second-highest sumo rank) and 陥落 (kanraku, fall/demotion).