Luiz's discipline and fouls would be flagged by now as he receives an iPad with instructions, data, and footage to improve his performance. Analysts and coaching staff, and especially Emery's instruction to detail of player would not have escaped them so it's purely down to the individual player , in this case Luiz, for the maturity, game intelligence, and emotional control.
Emery has said on Douglas Luiz. "He will face Lille in two matches. He'll rest against Arsenal and Bournemouth. Maintaining emotional control is critical"
That is the primary takeaway from Douglas Luiz's ten yellow cards and two match suspension, as he has previously been told and shown his fouls he's conceding after every game and it's been numerous times this season. Hopefully, this is a strong warning that his discipline needs to improve and his emotion in control.