Impulsive and Spread-himself-too thin superiors..

Being an employee, we could experienced different superiors..which we need to adjust and learn how to deal with them. But an impulsive superior is a kind I considered a" doesn't knew what he is doing. Same as true with the spread-himself-too-thin. That's what I considered my supervisor. Which in my Eleven years working in my present job, I experienced much stress when this superior came. The first was last year, and I promised myself it will never happen again. He may get stressed on me, not me on him. Just that situations happened. Just yesterday, I need to be appraised for recontracting. He mainntained my appraisal grade. In my previous supervisors, I used to asked and discussed about the evaluation. And got the same answer, "you deserve more, but this is I need to put as per policy". For some it might not be important, but for me, I wanted to know which area I need to focus, for some improvement. Yesterday, I asked him" do I deserved this, or did I not improved for the whole year?" His replied" I decreased the grades of, almost of the staffs. Ohhh...he evaluated me based on other staff's performances. I replied, "the field of work might be the same , but we are different persons". What is different" he replied. Huhhh...anyhow I told him, ok I will sign that evaluation but am sorry, I need to write some comments. Before the end of the day, the chief of staff called me, as he said my superior gave him my evaluation telling him, am not contented with my grades. Hahhhh...
Good enough, at least I was given a chance to speak out. So we had a long conversation. I told him, there is no issue here, I just wanted to know if I deserved or did not improved as the next question, what to do to have some improvement. As job is not just all about money, enjoying the job matters most, otherwise one will face much stress. Stress is one cause of death..lol Bottomline he wanted me to sign the evaluation. Yes, I will sign, but as was said, I need to put some comments..
This is what am going to write....
Supervisors, deserves respect and perform task assigned by him. I did asked permission to put some comments and he agreed. I want to say thanks for the evaluation, but I think, he doesn't know what exactly to do.
1. He doesn't know that evaluation is not about increment, it's about performance..
2. He doesn't know that evaluation is based on the staff performance and not based on the previous evaluation he did to other staff.
3. He doesn't know that the appraised grade is applicable for the present year and not for the next year.

Last year I asked him, why he decreased the staff's grade..he answered , it doesn't matter as the company stopped the increment. I explained to him that evaluation is not about increment, it's about performance..for long long years the staff work hard and earned the grade this supervisor came after 10 years and he decreased. He don't realize the consequence. I asked simple question he made it complicated ohhh..I should be thankful he did not decreased mine???he told me, I will increase next year ..tsk tsk...he really doesn't know what he is doing...