Afraid to Grade?

I can understand the desire of early twentieth century comp instructors to find what Connors and Lunsford term "a defensible rating instrument" (201). There is perhaps nothing scarier than having your grade challenged by a student who reads your comments but still can't understand why they got a C. I know instructors who use a grading scale. They assign a numerical value to grammar, thesis, organization, and their numbers are rarely challenged. This doesn't make their grade any less "objective" than mine, but somehow, students don't feel justified in arguing with a list of numbers that add up to a numerical grade. And in all fairness, a system like this has its merits. When I was grading papers for the online 203 class, I was given a grading rubric that I was required to follow. A paper was divided into five "gradable" sections and each section was worth two points. This meant that even if a student's paper was deficient in the "thesis" category, they could "score points" with perfect grammar and still pass with a tolerable grade. For an online class that spends so little time on writing instruction and offers students no opportunity for revision, this rubric seems like the only fair way to grade. But for comp instructors who work one on one with students, we need to have the ability to be more flexible. For paper one, I told my students that they needed to have an arguable thesis that was backed up with evidence. We workshopped theses in class; I gave them examples; and still, I got close to forty reports on various discourse communities. Admittedly miffed, I wanted to send a message to my students, so report-like papers automatically got a C. I believe this will force my students to pay attention to the assignment's requirements and revise their papers accordingly. I would not have been able to send this message if I was forced to adhere to a hard and fast rubric like that used for 203.
Like the example papers described in "Teacher's Rhetorical Comments on Students Papers," I spent a lot of time defending my grades in my end comments. As always, I began by making a positive observation, and then like most of the instructors in Connors' and Lunsford's study, I point out deficiencies and make constructive suggestions. I consider my students' feelings and try to make my comments beneficial, but they are often extensive and repetitive, a repeat of those given in the margins throughout each paper. I think I'm afraid of my students' reactions to their grades and worry too much about avoiding conflict.