Of all our kids who didn't get a chance here, how many of them have gone on to a top club? Phenomenal talent isn't that hard to spot, academies can nurture them but they don't make em. When you spot a phenom, you should go get him. The academy might some day produce some, and thos ones too will be fastracked like anywhere else. Truth be told, a good number of our academy players can make our main squad as role players, but almost none will project to becoming a star. So when there is a talent that look destined to become a star, you don't go "no, we've got kids in our academy who need a chance." Barca wasn't short of of talented wide forwards, Delefeou, Bojan, Assulin, Traore, Munir e.t.c coming thru their academy. When they chose too go for Neymar. When your evaluation suggests there' is a star in the making, you move for him.
I'm not saying I want Sane, simply pointing out the reason to not want him should never be 'our academy lads wouldn't get a chance.