I think he means the role has changed, which it has really. There's alot more emphasis in the modern game over 433 and variations of it. When you had a winger traditionally, he was a wide midfielder who would hug the line, whip in crosses and chip in with goals and assists. I don't think we generally play like that any more, the fullbacks do the wide midfield role and take up positions flanking the midfield. Our so called wide players push high up field, interchanging and often playing on the shoulder of the defender. Alot of the time it's like playing with a front two, Firmino provides the link between midfield and attack and often Mane and Salah push ahead of him and will come inside into more orthodox "forward" positions.
I don't think it's cut and dried to say we've got so many goals from a winger, that would be true if he was a player who supported the attack, he does most of his best work and gets most of his goals from inside the box. That's not to say he doesn't do good stuff deeper down the pitch, but he does the bulk of his best work in typical traditional striker positions.
