Someone on TW said this and maybe it's accurate - GOT is more of a BOA vanity project than something cooked up by SM or LSM. Maybe she convinced the execs at SM to give her a chance to regain her former glory by being put in the center of an Avengers GG of SM.
Problem is that she doesnt understand that throwing random members into random groups doesn't guarantee success.
If she wanted to comeback, she shoulda done it all on her own. Look at the MMM members, look at Jessie, Sunmi, and Hyolynn, all veteran idols pushing 30 or more and still busting ass working furiously to make music and remain relevant. They put themselves out there to succeed or fail on their own.
I don't know anything about the rest of this, but BoA has had multiple comebacks. Last year, she came back with "Better" in Korean and "The Greatest" in Japanese. She was also a host for two different shows last year. She really has not had dead space since she debuted in 2000.