What we are seeing with Barkley, similarly to Stones, is the product of 3 years of almost no defensive coaching whatsoever.
Barkley is atrocious off the ball. I've never seen a defender able to catch him when he's sprinting with the ball at his feet, but how often does he use that explosion going the other way? The manager does not demand that he tracks back, that he sticks to his man on set pieces, that he presses opposition or that he makes tackles and cynical fouls when needed. Barkley is asked to conserve his energy and spearhead our counter attacks, something he has done well this season.
I always think back to that Norwich game, where he scored his first goal. He was flying into tackles, battling to win the ball, and was outstanding driving forward. I don't understand the logic in coaching that combative style out of him.
Credit to Martinez for giving him as much game time as he has but i'm far more excited to see what a better manager will get out of him. Barkley is one of the best talents we have ever produced and i'm sure whoever comes in will be looking to build his squad around him. I can't wait.