It is well known by the readers on this site that I am in no way a fan of David Luiz, however, in the interests of balance, it is only right that I highlight the positives that the Brazilian brings to Arsenal.
Luiz does come with baggage, there is no denying that and we have already seen that baggage in action and it cannot be argued that he is not a complicated man but it is not all negative.
Knows how to win
Luiz has won almost every major trophy including the Champions League, Premier League, Europa League, Primeira Liga in Portugal and Ligue 1 in France. All clubs need players that know how to win and Luiz certainly fulfils that criteria.
Immense experience
Obviously, when you win so many trophies you gain experience, however, experience comes in many different shapes and sizes including the 7-1 loss to Germany in the 2014 world cup semi-final when he captained his country. It takes huge character to come back from that and when you do experience something of that magnitude you learn from it and I have no doubt that Luiz has done just that. His experience is crucial when the chips are down.
Mentoring the youngsters
All that Luiz brings to the game, how to win and experience he will be passing on to the Arsenal youngsters, just by having him in the squad is enough, they will see how he conducts himself, how he reacts and bounces back, how he deals with criticism but also how he plays the game. That is invaluable.
When he is good he is very good
Putting aside his chaotic errors of judgement it cannot be denied that he is a very talented footballer, he can score some beautiful free-kicks, he has the ability to make pinpoint passes, can whip in a ball with precision, shows great leadership and knows how to defend at the top level. It has always been his consistency that has been the issue, not his talent.
Conclusion
Luiz has many negatives in my opinion but I am not blind to the positives he brings to Arsenal and I sincerely hope that it is his positives that we see far more of.