The most important lesson must be, how do we improve due diligence when forking out huge sums (Mendy £50m+) on players. Clearly a deeply flawed person, why did we not have any idea Mendy was a ticking time bomb.There a risky types eg Mendy, Mario, Tevez and now Jack who off field are/were not always professional. In most cases they cause serious issues down the road. It's a really fine balance to make the right judgement but it's something else we have got to improve. Dare I mention, Ronaldo who was obsessive as an athlete but still ended up settling out of court for alleged rape. Time to draw a line and move.