#1 Add pace to the wings
When Neymar left Barcelona for PSG at the start of 2017-18 of the campaign, Barcelona lost someone who provided them pace on the wings and scored a ton of goals. To fill his gap, Barcelona signed Ousmane Dembele from Dortmund for a reported fee of €120 million. But his campaign got disrupted when he injured himself in a League game in September and was forced on the sidelines for 4 months. This forced Valverde to play with a 4-4-2 formation which relied on the hard work of the midfield and the solidity of the defense.
Since returning back from that horror injury of last season, Dembele has been in and out of the team and has struggled to nail down a spot in the starting XI thanks to his niggling injuries. This means that the coach is left with no choice but to start Coutinho on the wings who provides no pace on the wings and is more of a liability for the team. Some might argue that Valverde should use Malcolm but he is someone who seems to have no trust of the coach and has really struggled for game time this season.
This has made Barcelona attacks one-dimensional. Their only attacking option is through Luiz Suarez who is man-marked by defenders as there are no wingers in the team who can stretch the play wide and force the defenders out wide thus creating space for Suarez to exploit. Hence signing a winger who is injury free and can score goals thus reducing the burden on Suarez and Messi is a must. This would mean the club could probably loan out Malcolm or even sell him if a decent offer comes and get rid of Coutinho as a whole.
Julian Brandt of Bayer Leverkusen and Hudson Odoi of Chelsea are players who would both cost the club below €50 million, add some serious competition to Dembele and give the club tactical flexibility when required. Hence, Barcelona should seriously think of bringing a winger to the club which would improve the squad on the attacking front.