He doesn't make those runs all that often cause he doesn't have an eye for them. Any player can make a great run here and then but its the ones that make then consistently that get lots of opportunities to score goals and rack up great numbers. Ashley Young is not that player.
Barca have stopped over commiting and this has paid dividents as they are defensively as solid as they've ever been. Certain players in the barca team rarely run into the box and in front of the ball. These are the players that enable them to defend well when the opposition team has the ball. Their 3 midfielders don't go rushing into the box to often unless the opposition has decided to all defend into the box. They used to have both fullbacks to far forward causing them all sorts of problems when defending counters, that stuff has come to an end.
Bayern were lucky they always had Ribery who'd be a dual purpose player, especially in the big games(hence bayern fans often refer to him as their primary playmaker in those days). He'd make it a midfield 3 In such games, and then provide a wide threat during the same match. Robben all the time was a wide forward, always cutting in and finishing moves, especially in transition. They played almost exclusively outside in, by that I mean they used to take the ball wide, then go inside as the true width(ability to go for crosses and such) would then be provided mostly by the fullbacks. That way of playing is distinctly different to our united way of play that we utilised in the 90's and early 00's. The same stuff we brought back with Valencia, and Young after losing Ronaldo.
Players like Young and Valencia who show no versatility in the game are a weakness to attacks unless they are played at fullback. City have the same issue with Navas as when he's on the field they don't have enough players to go through teams through the middle.
To clarify, by wingers I mean players who's main job is to run the line and get balls into the box.