I'd say the examples you said are mainly training issues ,with the exception of jacking after 10 runs.
Now if it's jacking after 10 runs ,I'd say 10 runs on what , is the dog injured or Unfit, or been given Unrealistic slips near hedges continuously as a youngster.
But if an animal isn't physically fast enough or capable enough for why you bought and raised it for, maybe then it hasn't made the grade. A dog that don't want to try can also make you fallout with it.