First off, Sakho was never 'by far our best defender.' He's as consistently inconsistent (nods to rh) as the rest of them. One week he'd be brilliant. The next two utterly abysmal. Never have and never will understand where this cult following has come from with him?
Secondly, his 'attitude' problems go right back to Paris where they ended up bombing out one of their own, the club captain at that, down to his indiscretions. And it continued at Anfield long before Klopp. Larking about in training. Having a lax attitude to his work. Rodgers wasn't strong enough to stand up to it. The German was.
Thirdly, and related to the above, contrary to what you apparently believe, the club stood completely by him through the doping/ suspension saga. All that was self-inflicted from the man himself. To then have him turn around and come back with the same P poor attitude the summer before last. Initially causing a delay of the flight out to the States due to going home and 'oversleeping' after the Huddersfield friendly when the rest of his teammates stayed together for a meal before the flight. Then missing further meetings/ physio sessions, and acting a complete childish ***** out in America. It was a culmination of a multitude of indiscretions that cost Sakho his Anfield career. After the manager who apparently 'could have done more' had stood by him through his suspension and welcomed him fully back into the fold with a clean slate the following pre-season.
NOBODY is to blame for Sakho not being here other than Sakho himself.
Being a complete disingenuous ____ and celebrating Crystal Palace goals, at Anfield, when he was still under contract as a Liverpool player, made worse by the fact he wasn't even on the pitch but came the touchline to celebrate last season was beyond the final nail in his coffin. If Klopp had brought him back into the group after all of that, and the stance he'd taken, it would have completely undermined his authority within the changies.
Not sure what a photie of Mainz players celebrating has do with anything like but there you go.