Envy's problem is Happy bad support and lurker. Kio should have not been replaced.
Kio - Used to be entry (relied on his aim), was moved to a mid round player - relies on mental competence and great intuition of the game.
Happy - Lurk, relies on his mental solitude and competence.
Kio was the weak link of the team, his role simply wasn't working out. Apex was moved to entry, Kio was moved back (Mid round / 3rd / 4th guy onto the site). He was always a player that manifested his skill through raw aim, coupled with the fact that he had no work ethic (According to NBK) is what contributed to him being kicked. A great replacement for Kioshima would have been Shox. One more thing, Kio had a sub 1 rating in the past 5 lan events he attended with EnvyUs.
Happy is a great player but from what I've heard his work ethic coupled with Kenny's frustration and rage when he does bad really seems to be what contributed to nV's problems. I think Kio also said in his statement that they simply weren't respecting him. Imo Happy really reminds me of a French Flusha. Incredibly cocky and ballsy and really doesn't give a fuck. The kind of guy who types GG in chat whenever it's a losing match point and his teammate is in a 1v3 situation. If it's your full time job you should be respecting all of your coworkers and working to be even better.
If you depend on your aim and have no work ethic to practice and polish the skill you solely rely on is a good enough reason for your teammates to lose respect for you.