I'm not sure Brentford have got much benefit from closing their academy.
I think they thought that with so much competition in London for youngsters (closest neighbours QPR and Fulham I guess, with Chelsea not too far away as is Spurs and Woolwich) that they were not getting a great crop of youngsters. However I'd guess they've had a fair few decent prospects - and as we know its only the top 1% or 2% likely to make it from those that start aged around 10 years old or less, and even at kids in the academy aged 16 or 17 even one player a year making it is a decent haul.
So I think the bet very simply was that they could pick up a lot of discarded youngsters from Chelsea, Spurs Woolwich and others at aged 18 and more easily polish up those players rather than doing all the heavy lifting on the younger ages which would have a lower average 'quality' intake.
A couple of Spurs youngsters such as Paris Maghoma (E u18) have gone there as he thought he wasn't getting enough recognition at Spurs, but not sure they've succeeded with too many youngsters like him who they picked up from larger clubs. And they did lose a few decent players when they closed their academy (Timothee Lo-Tutala being perhaps the best prospect).
Now they are in the PL where playing standards are higher the chances of our discarded youngsters being good enough at Brentford doesn't seem a good bet, and neither did it seem to work when they were in Championship. So not sure where they go from here !