Tbh there's probably quite a few teenagers who were better than Gerard at 17... Neymar (but no one knows if he'll implode, he's brazilian after all (+ attitude)), Lukaku, 'the new Messi' (paraguayan kid who plays for Argentina and recently signed for Porto... And then there's the 16-year-old wonder kid known as Coulibaly (scored 8! goals in u17 World Cup for a distinctly average Ivory Coast, many of them spectacular), + a few Mexican u17 world champions could be thrown into the mix.
Liverpool have Sterling and Suso, both look extremely promising. United have this Pogba guy. etc etc
But remember that Gerard could explode this season as he'll face better opposition, thus forcing him to evolve (or his development will slow down).