Chiellini should never attack. Ever. When he gets the ball he should be under strict instructions to pass it to the team mate closest to him as soon as possible. Anything else just isn't worth the risk.
I'm not just criticising his play going forward. He's constantly out of position, he makes rash decisions that you'd expect to see from a kid, every first touch is a disaster waiting to happen and even the simplest passes are beyond him.
He seems to be getting worse. His touch, passing and decision making are outrageously bad. Even his defending isn't reliable these days. I honestly have more faith in Ogbonna and Bonucci at the moment.