No offense to anyone, but it's kind of easy to "prove" you're worthy of replacing someone who barely had any development up until her death episode.
I'm actually saddened Mitich is seemingly going back to being a generic bridge officer. The bridge is already very crowded (Rhys, Detmer, Owosekun, Saru, Burnham, whoever is Captain, Tilly). I thought the recasting was to set Mitich up as Chief Engineer, which would have her hold her own scenes in Engineering (which is usually empty other than Stamets). The Chief Engineer has been referred to multiple times, but has never been seen (and I still don't know if Dr. Pollard is supposed to be Chief Medical Officer?)