Tbd I'd say Arsenal made Fabregas the player he is today, I know he was at Barca until he was about 16 but it wasn't like Pique where it was essentially a loan deal. Fabregas was one of the best CM around 09/10 because he emerged as a leader which he isn't at Barca.
As much as I utterly despise him I agree with Zurich that Reus wasn't homegrown. There's so much more you learn as a pro even in the German 3rd div than as a youth player, physiciality, mentality, pressure etc