Cally, you're getting confused cause you beleive there is only a 442 formation. Alves gives us the opportunity to play 352, 4312,451 etc. We struggled to change formations last season because of a lack of quality in certain positions. Alves and Speedy imo are very important to Rafa's masterplan. They give us pace on the wings, they give us the chance to play with three at the back against weaker teams and of course they can also be used as impact subs when we are under the cosh against stronger opposition.