Not many players have left Liverpool and gone on to better things during Jurgen Klopp’s reign. The Reds haven’t always let go of certain players at the ideal time, with some outstaying their best by a year or two. Despite that, the ones who have gone with something left in the tank have usually found it running on empty pretty soon after. Last summer’s batch of departures from the Liverpool squad are good evidence of this. Jurgen Klopp let some big players go, including a number of bona fide legends of the club. But while Roberto Firmino has struggled to get going in Saudi Arabia and James Mil…