How to you tell your sensei (with respect) their waza isn't as good as it once was a few years ago. That due to neglect of skill. To provide a common and universal fictional example, such as, focusing on teaching and neglecting their personal training, has resulted in the deterioration of skill, and stagnation of personal developmental training. Because you respect your sensei, you just don't want to tell her, theoretically, she is as good as she was a couple of years ago. That is has become just the opposite, and if you don't get it together I finding a new dojo. It is a complicated situation where I am not going to just abandon her, after all the time and effort she has put into me as a teacher. I am not going to abandon her because her skill level has slipped over last couple of years, simply because she can't hold the mark. Because you respect her, as she is your sensei and shows up to class, giving of herself, you want her to regain that lost skill, she once had. You want her to shine, You don't want other students out performing her to the point where new students are giving more credibility to the assistant Sensei whose skill and technique is clearly better, now that hers has slipped. And no she isn't injured or old.
So here we have a young lion [you]saying that the sensei is not as good as she was. You then state the other students are thinking the assistant instructor is better. My own view is this , you do not appreciate a lady who may well have sacrificed her own training to help you and the assistant instructor.Instead of belly aching and being critical , just train .If you cannot do this , get out of the dojo.
I for one would not miss you if this was your mindset.Anyway , comparisons between Sensei in my view is wrong.Each person brings something to the table.What do you bring to the table[apart from criticism? Joe.