再者,研究型的毕业重点是在你的defense和thesis上,如果你的committee对你的defense或者thesis不高兴,就算其他的课修得再好,都不可能毕业的。Else, if your committee members are happy with your research results, also you are eligible for the minimal requirement for graduation, no one cares what marks you got for all your courses.
Anyway, you may check the degree audit with your university and there should be a balance between research and course work.