Messi does best when he drops in between the two lines of defence, as a false 9 where he can receive pullbacks and create space for wide players. It's a misconception to think Messi in midfield is holding him back because that's the whole purpose of a false 9. However, there are certain times when he drops way too deep, or in the case of Argentina where hardly anyone can link up with him and he is bascially creating chances alone for 4-5 players upfront who has zero aerial threat or composure in front of goal. Against Ecaudor, he moved up to more advanced position instead of his ultra deep positions against the likes of Venezuela or Peru.
And we do lack abit of width, of course Messi has Alba, but when Valverde uses Roberto as RB, it is definitely heavy work and punishing for the fullbacks. Few times the defence got caught off guard by Espanyol, especially the instance when Roberto tried to create from a deep position and Rakitic tried to move up the flank and support, but Roberto got dispossessed halfway through, allowing them to fully exploit our right flank with Rakitic missing from his position. Messi had to then drop very deep to collect the ball to cover the mistakes by those two.
It's also a misconception that 442 is "safer", especially when u have Rakitic and Roberto to do offensive and defensive work.
I strongly suggest a 433 if Roberto is used as a right back, and Semedo AND Roberto to be used if we are playing a 442. Because it is dangerous creating from deep positions, and the lack of a wide player to transition the ball quickly.