As Phil says, once off the lead we are spectators. Dogs with high drive are more at risk than others, but then recklessness is a good trait and proves honesty,and the more honest and driven, the happier the dog is in expressing himself. If he runs into a telegraph pole thats just bad luck all round. To quote Delboy "He who dares wins"
As already said by Socks I think, puppies need to have free running from 10 weeks old and learn to use themselves. That makes all the difference.