Add to this, if you look at the whoscored stats for 13-14 when Cuadrado played about 75% of his matches in attacking positions he still had vastly better defensive stats, passing stats, long ball stats, dribbling stats, etc.
Far better all around player, and equal to Salah when looking exclusively at attacking output when they are playing the same position.
Not to mention they are 2 very different types of attacking wingers. Cuadrado being a more traditional wide winger with fantastic crossing ability and the skills to play alongside a CF, whereas Salah is terrible at giving service to a CF which is part of the reason Dzeko has sucked so badly for Roma. He's a goal scoring winger who plus inside, can't cross worth a damn, and isn't a particularly gifted passer.
As in, all Salah offers is goalscoring. Whereas Cuadrado offers passing, crossing, long balls, and defensive contributions.