Year 2019. No elite boxer in MMA yet.

It's been more than 20 years, but no sign of elite boxers in MMA. Almost most major disciplines had someone who showed their effectiveness in MMA. The list is long.

Taekwondo - Pettis. Third dan
Shotokan Karate - Machida Third Dan
Kyokushin Karate - GSP Third Dan
Judo - Fedor Fourth dan.

Sports Sambo - Minakov Multiple time world champion
Combat Sambo Khabib Multiple time world champion

Freestyle wrestling - Romero...

Year 2019. No elite boxer in MMA yet.