#4 EC3
Former WWE 24/7 Champion EC3 has not been a part of RAW for the last few months. His most recent TV match took place on an episode of WWE Main Event way back in September 2019, where he teamed up Eric Young in a losing effort against Lucha House Party's Gran Metalik and Lince Dorado. EC3 became a legit star and World Champion when he went to TNA/Impact Wrestling, and when he returned to NXT, he was immediately treated as an important Superstar.
With the exception of some silly moments spent (literally) running after the 24/7 Championship, EC3 has done essentially nothing since joining the RAW brand in January 2019. He has only had a handful of TV matches, as he has been primarily used on Main Event, which is only aired on TV internationally (though it is available on demand on the WWE Network). It's needless to say that EC3 has suffered through a very disappointing run since the being called up to the main roster.
A top AEW star just called one of his colleagues 'spoiled' and 'narcissistic' HERE.
He was taken off TV in November after suffering a concussion, so hopefully his injury isn't too dangerous to the point that it would prevent a return. If he's healthy and ready to get back into the ring, WWE would be well-served to move him to SmackDown and allow him to realize his full potential. One big opportunity would see him team with Daniel Bryan and Drew Gulak, who could definitely use a teammate to level the odds against Shinsuke Nakamura, Cesaro, and Intercontinental Champion Sami Zayn.
Bryan helped Gulak become a top name on the main roster, and he can do the same job for EC3.