Sort of agree with that too. Had a lurcher bitch, quite a few years ago now, that was showing good signs as a working dog, up until she got to about 2 1/2 years old. But she didn't level out weightwise, and was very powerfully built, 29" tts 80lbs, and never learnt to use her speed and weight to her advantage. Caught a few things, but on rabbits she wasn't even fairly useful