Well toe might have been a little worse than .1 but I can't remember exacts at this point. A tire defect is possible, as is worn bushings and struts and possibly ABS. Again not alot of people are going from 120 to 30 in 20 feet like they do on the race track so the likelyhood of this being a ABS issue on a non-riced out focus driven by a female foreign college student is highly unlikely. Again not trying to rule anything out but the fact still remains I've seen this alot and 8 times out of 10 it's a toe issue. Dog tracking still doesn't equal out rear toe. The reason it equals out in the front is due to the fact that the steering gear/ rack equals itself out due to it having that capability with moving parts. The rear is set and tightened (unless obstructed by way of bent parts, collision, etc.) without anyway for it to completely equalize like the front ( unless you want to get wayyyyyyy technical about this and start in on the aws vehicles). Does dog tracking come into play here? A little. but dog tracking is mainly when you have a solid rear axle or there is very extreme deviation in toe from one side to the next. In this case I really believe that it has everything to do with neglect to rotate tires and a toe specification issue on just that left rear.

I agree that a weak shock can help accelerate this flat spot, and I did not drive the car before aside from pulling it in and replacing both rear tires and doing the alignment.