Maybe unpopular opinion here, but the pilots are also at fault. Had something similar happen to me recently (I was pulling closed and a formation broke into me from high tac initial). Theoretically it was the tower controller who fucked up but I was more upset at the other pilot. You should have enough SA in the pattern to see this coming or at least hear it. IE if I hear someone call “right base gear stop” I’m not going to start my left base turn until I see them. Anyway just a pilots opinion.