Paul Snyder retired after 2007. That's when the farm went downhill. 2008 draft produced 5 major leaguers, Spruill, Kimbrel, Clemens, Oberholtzer, Hoover. 2009 produced 2. Minor and Hale. Maybe 3 if Northcraft can ever make the jump.
2010 first year after Clark left, Cunningham, Simmons, Gosselin, Terds, Shreve, and Gattis, and maybe some more as Drury and Leonard are both in the upper minors. 2011 Ahmed, Graham, La Stella, and Schlosser, With guys still in the upper minors Gilmartin, Kubitza, and Martin. 2012 has produced as many major leaguers as 2009 with Wood and Simmons. and of course we still have Sims in the upper minors.
You may be thinking, what about international guys? Well we did net a big one in 08, Julio Teheran. But I'm pressed to think of others. Could be my memory failing me. But it's not like Wren and co sucked at getting international signings, Peraza, Mejia, Albies, Camargo, Cabrera, and other guys who have value to our system were there.
To me the greatest fallacy is that Wren wrecked our system. He restocked our depleted system that JS left him with and 1 mediocre and 1 poor draft left him with not much in the minors. So he went out and got guys to stock our upper minors and build our depth.