Arthur has been arguably one of the best signings for FC Barcelona in recent years. Barcelona's midfield has been pretty static and out of sorts since the departure of Xavi in 2015. During his prime, Xavi was the metronome of the team and was the most involved player throughout the whole game.
Barcelona tried to replace the outgoing Spaniard by signing the likes of Ivan Rakitic, Andre Gomes and even Paulinho. While Rakitic is a much more direct player than Xavi, the likes of Gomes and Paulinho simply did not have the skill set of the 2010 World Cup winner.
However, in Arthur, it seems that they have finally found their much awaited long term successor to Xavi. In addition to that, Barcelona's midfield finally looks more sorted compared to last two seasons, wherein Messi had to drop back to help out the midfield.
On the right side, Messi stays central and plays almost as a no. 10. Amongst midfielders, Rakitic is the most advanced of all, while Arthur is the one who dictates the tempo of the team's play along with Busquets.
The above image shows how Barcelona look during their buildup. While the wingbacks push up high and occupy the wide space, the wingers tuck in. Dembele plays as a wide left midfielder in this system and has the license to cut onto his right foot and drive at opponents and operate in the left attacking half space when Messi drops deep.
The presence of Arthur as a controlling midfielder allows Rakitic to drive forward from midfield and link up with Messi and the other advancing players. This prevents Messi from dropping too deep and allows him to have a greater influence in the final third. And just in case Messi does drop deep into the midfield to control the play, Rakitic moves forward and occupies Messi's position.
In the presence of Iniesta or Coutinho in the midfield, Rakitic had to play as a holding midfielder, where his attacking prowess was underutilized. However, with Arthur, Rakitic has much more freedom going forward. In addition to that, Rakitic does track back as well to support the midfield during a defensive transition, or in case Arthur moves forward to press the opposition or link up with the advanced players.
However, it is important to note that all three midfielders are very versatile in their style of play and often switch positions on the pitch which makes it very difficult to mark them. While Rakitic is the one who drives forward most of the time when Arthur stays back, either of Busquets or Arthur also move up to occupy forward positions, occasionally while Rakitic hangs back.
Moreover, Arthur is much less direct than Rakitic which makes him a perfect candidate for the role of a controlling midfielder at Barcelona. He stays closer to Busquets which helps him during the buildup phase and allows the entire midfield to dictate the play from the middle with ease. Furthermore, he understands Barcelona's style of play pretty well, and always makes himself available as a passing option while building from the back.
Conclusion
It is fair to conclude that Arthur has been a revelation for Barcelona this season. He has the 'Barcelona DNA' instilled in him and the Brazilian could finally be the Xavi replacement Barcelona fans were crying out for.