Another thing they could have done was draft a bit better, particularly in the sixties and seventies, when, sometimes, the difference between boom and bust was a pick or two away...
1965 draft: Take Johnny Bench (taken 36th) in the second round (pick #24).
A little more than a pick or two (twelve picks actually) away, BUT, I don't know if there's such a thing as reaching in baseball drafts.
Especially when you consider that Bench was a high school standout from just across the border in Oklahoma.
If they don't take Bench, they still could have grabbed a great catcher three years later...
1968 draft: Take Thurman Munson (#4 overall) instead of Martin Cott at #3.
Literally one pick after the Astros took career minor leaguer Cott, the Yankees took a guy that was the heart and soul of their team for almost a decade, before his untimely and tragic demise in a plane crash in 1979.
Cott was a catcher, so you know the 'Stros were looking for one that year.
Deep pick in 1968: Cecil Cooper at 111th in the 6th, seventeen picks ahead of the Red Sox.
One thing I noticed about the Astros was lack of consistent power bats in the line up for long stretches of time, particularly in the seventies.
I don't know if it was the Astrodome having an adverse effect on the hitters, but there's a couple of hitters who could overcome such obstacles...
1971 draft: Take Jim Rice (#15 overall) instead of Neil Rasmussen (#12)
Rice could rake, and would have been peaking around the time the pitching was turning into a world beater.
1974: 1st round, 15th pick, the Astros took Kevin Drake (career minor leaguer)...next pick? Lance Parrish, eight time All Star catcher and first baseman, 324 career homers, taken at 16 by the Tigers.
Speaking of pilfering the Tigers...
1976: Alan Trammell was the second pick in the second round that year, #26th overall...1 pick after the Astros took Philip Klimas. Yeah, I never heard of him either.
Solid defensive short stop with a solid bat who could steal a base.
1976, 5th round, 97th pick overall. RHP Joe Isaacs. The Tigers took Jack Morris, also a RHP, with the 98th pick.
In the 1980's, no starting pitcher won more games than Jack Morris. Isaacs...never pitched in the majors.
1978 draft: Take Kirk Gibson (drafted at #12) instead of Rod Boxberger as the 11th overall pick.
Gibby would be in the majors by '79, bringing a combination of power, speed and average with him.
He didn't get much playing time with the Tigers until 1983, while Steve Kemp and a revolving door of outfielders kept him from getting regular playing time.
In Houston, I think he could have been a regular much quicker, on those early eighties teams sporting Rice and (perhaps) a healthy JR Richard, Nolan Ryan (perhaps they keep Floyd Bannister, the #1 overall pick in 1976) giving them a solid arm from the left side) and the rest of the pitching staff, Jose Cruz
In the first round in 1977, they could have taken Bob Welch at 14, before the Dodgers took him at 20.
So there's a way the Astros could have built up through better drafting too.