Luhnow was never in charge in St. Louis. It seems to be becoming a myth: Luhnow's success in St. Louis. Yes, it appears that he drafted (and acquired internationally) somewhere between OK and very good, but he was never the GM, never made trades, never constructed a club, and who knows if he even made the actual picks.
From 2006-2010, Luhnow was not only in charge of scouting out draftees, he was also in charge of player development for the guys in the system. And if there's anything I've learned from lurking these boards, it's that drafting the right guys is only half the battle...you've got to develop them properly, too. I liked the idea of a combined scouting/player development guy when the Cards were doing it, on the theory that with a cohesive system like that, you'd be more likely to draft guys whose talents and attitude will play well with the team's development program.
So in short, Luhnow wasn't in charge in St. Louis, but being the head of both scouting and player development do (which I'm not sure I've seen any other team do) seems like a pretty good dry run for constructing a club.
Some stathead, who is actually true to their allegiance, should take the WAR (or whatever stat it is) of St. Louis over the years, and break it down amongst the players. See how much was acquired through the draft and internationally, or came from pre-Luhnow players or trades.
Viva El Birdos did something like this recently.
(Link) The upshot: Since 2008, the Cardinals have gotten more WAR-based production from "homegrown" players than outside acquisitions. Each year from 2009-2012, the Cards got somewhere between 24 WAR and 29.5 WAR from guys who were drafted or brought into the org at AA or lower. For reference, if I can operate Fangraphs properly, the entire Astros team only put up 27.1 WAR in 2009 (their best year from the same time frame), and that's when Bourn, Wandy, and Pence were contributing 4.9 WAR, 4.0, and 4.0 WAR, respectively.
You can quibble with the methodology a bit--in 2012, they got 6.5 WAR from Yadier Molina, a guy that Luhnow neither drafted nor developed--but they've gotten a lot of positive value from their farm lately (Jon Jay, Allen Craig, Colby Rasmus, Skip Schumaker, Brendan Ryan, Lance Lynn, Jamie Garcia,).
Hell if I know whether Luhnow will wring good results from this Astros team, but the process feels right.