Don't get me wrong, I'm not against the loan back to Feyenoord. But, for me, it might prove just as beneficial to his game for him to spend a season living in England, getting to know his team mates, learning our style of play in training, improving his weakness and his game generally under Wenger's guidance, etc - it's hard to say exactly what would benefit him more.
Add to that, we don't really know exactly how good the kid is. Look at the impressive jump he made from high school football to the Eredivisie, playing and training with better players/coaches he may have another level in him pretty quickly, similar to Jack or Szczesny - which would then make him a good squad player.
