Absolutely yes, he is getting the best out of them. Many of our players aren't good enough. The ones that are he's turning into superstars - eg Bissouma and Lamptey.
Burn probably did enough in training to warrant a place in the team. Potter doesn't have crystal ball, but if he did he absolutely wouldn't have picked him.
Was the Arsenal game not a crystal ball? The one where the goal was scored by a pacey winger beating him?