Though i know what you mean, in the field there are too many variables BUT as said, a lurcher should ONLY be judged on what it catches and it dont matter how feckin fit you think your dog is, if it catches feck all, it's shite...!
I suppose it's the same with gun dogs. sheep dogs etc bosun if it does the job that's good enough. I just find it strange that folk say it's 100% fit when it can't possible so.