Kepa Arrizabalaga has been here before: a new manager, a clean slate, the chance to start over. By now, after all the trials and tribulations, the Spaniard probably knows not to get ahead of himself. It has been four years since Arrizabalaga turned up at Chelsea, all bristling confidence and youthful innocence as he insisted that becoming the world’s costliest goalkeeper was no big deal, and...