70 on an ochem test is honestly not that bad. That would be considered a good average if the tests are objectively challenging (like asked very applied or theoretical questions). if they are rather straight-forward and the grading is just unnecessarily harsh then that is most certainly a low mean. For example, with instructors who give VERY challenging exams and to people who have mostly earned B+ and higher grades in general chemistry (these stronger students self-select into harder ochem sections where I went), a 65-75 would be a very solid performance.
Also, please remember that AP is curved and sometimes (ok, basically never) a 5 does not correspond to a super high (or even high) score much like an A in a college course does not necessarily correspond to a 93. In addition, general chemistry simply does not prep well for the structure and concept oriented nature of ochem especially in the case of challenging and/or fast-paced instruction. I feel only gen. chem 1/2 performance is a fair metric to use and even that has imperfect correlation (with most AP 4/5 receiving a B grade and 4’s often equaling the 5’s performance).