Pretty much this. Teams literally never have to worry about our right side because even if we switch play out there, we never have anyone there (Lingard, Mata doing shit number 10 impressions) or Young who will do absolutely nothing with the ball. As a result the left hand side gets so crowded.
Football is pretty simple, you stretch teams out by making the pitch as wide as possible making the opposition team defend as much space as possible. It's what City do through their wide players and Liverpool do via their full backs. Teams get so tired tucking in then sprinting out to get to these players chances are made. We instead have an attack where everyone thinks they're Riquelme, playing off a non existent front man, trying one twos in the most crowded part of the pitch making it super easy to defend against. This is why the only decent football we've played under Ole is on the break, we still have no clue how to build an attack.
A right back that actually stretches the right side and holds width would help with this massively.