I don't have much to offer you. But I recently glanced our starting pitchers' game logs and found something slightly encouraging (or at least, something that might console you going into 2013 without two of our most effective starters). If you're looking to our rotation to improve next year, there are a few areas you could expect that from: Norris regaining some of his 2011 magic, Lyles (age 21) learning to keep the ball down, and somebody else from AAA or a low budget free agent keeping you in games from time to time.
Unfortunately, there are also some areas where you'd expect it to be worse. Namely, replacing Wandy Rodriguez and Happ, and Harrell's regression. Encouraging news on two of those fronts: despite being our "ace" and having a solid, albeit unspectacular season, the Astros were 7-14 in games that Wandy Rodriguez started. And while Harrell might be outperforming expectations, the 'stros are still just 7-13 in games that he starts. In other words, the Astros have a .34 win percentage when their #1 and #2 pitchers are on the mound this season; identical to their total win percentage.
As for other pitchers, the Astros are a deserving 2-11 with Lyles on the mound, 8-10 with Norris pitching (despite the 5+ ERA, he registered quality starts in 7 of his 8 wins), and 8-10 with Happ on the mound (with 12 quality starts to boot). They're also 1-5 with Keuchel pitching (though he has given them a good chance to win three times).
What does it all mean? Probably not much. The bullpen and offense tend to dictate wins. I submit that the Astros have faced some tough luck in terms of matching good pitching performances with clean bullpen outings. But when it comes to next year, I think the following things are likely:
1) Norris will pitch better (though I suppose his record could get worse).
2) Harrell might not pitch as well, but the Astros' record during his starts won't suffer for it.
3) Our winning percentage can't reasonably get any worse with our #5 pitcher on the mound (18% with Lyles and Keuchel).
4) Somebody (Weiland, A. Rod, [insert free agent here]) will pitch well enough for the Astros to replace that 7-14 mark with Wandy on the mound.
That's all blind speculation, of course (sorry, Sabermetrics people), but the idea that losing Happ and Wandy is going to cost us wins next year doesn't have to be true. It's just a matter of Luhnow getting a little luckier than he got this year and finding somebody more effective than 2012 Jordan Lyles.