How did Guehi 'assist' allow Barry to score when offside?

Barry was waiting on the shoulder of Guehi, weighing up when to make his move as Rohl played a through ball. It was not a good pass by the German midfielder, straight to the feet of the Manchester City defender. While Barry had started to move towards Guehi, he was not placing the opponent under pressure. Inexplicably, Guehi under hit a back pass which Barry latched on to to score. …