I decided to go to the wonderful www.baseball-reference.com to find out. I started at Marwin Gonzalez and looked at his games and plate appearances. Last year was the first year he had over 500 plate appearances. A lot of that due to the fact that the Astros could not find a regular first basemen. Marwin has been with the Astros for 6 seasons and 519 games. I started to look for Astros' players with similar years and games played. I then went and looked at their WAR on Baseball Reference and compared it the number of years they played.
Cliff Johnson spent 6 seasons with the Astros and produced 5.8 WAR. He was atrocious in the field and mainly contributed as a pinch hitter. His 9 offensive WAR (oWAR) and -3.3 defensive WAR (dWAR) proves that.
Marwin Gonzalez has 5.2 WAR in his 5+ seasons with the Astros. I was a bit surprised by that when I saw the numbers. He has a 91 OPS+ for his career. One would assume that the Astros gain from his defensive value. That is not the case. His 4 oWAR is higher than his 1.8 dWAR. In 2014 Marwin played at every position except catcher, pitcher, and center field. Last year the only position he didn't play was catcher, pitcher, and right field.
Jake Marisnick Yes, swoon (as the Astros ladies like to call him) to this point has been a good contributor off the bench. If I was surprised by Marwin's numbers, I was blown away by Marisnick's numbers. I mean he's essentially a defensive substitute. That's exactly what he's done in four seasons with the Astros. His dWAR is at 4.9 and his oWAR is at .5 giving him a total of 5.2 WAR.
Denny Walling should probably be below Jake based on averages. The dude played 13 seasons with the Astros and put up a 14.1 WAR. I have to take into consideration the longevity. All of his value is in his 13.4 oWAR. His dWAR is -1.8. Which is weird because the math doesn't add up. This is why people have a hard time taking WAR, seriously (Explanation on WAR in comments. TL;DR I'm dumb).
Bill Spiers, as I recall, was a utility infield. I had to get confirmation, though. 8.2 WAR in six years is pretty good. His bat produced a lot of that value 8.5 oWAR compared to a .4 dWAR. Looking at his positions he played all over the field. In 1999 the only position he didn't play was catcher and pitcher.
Honorable mentionsGeoff Blum and Casey Candaele. Blum was a pure infield utility player while Candaele played a some outfield. They both spent five years in Houston. Blum accumulated a 2.5 WAR. Candaele accumulated 3.2 WAR.
It's entirely possible that I missed someone. I would love to hear of other players you think could be in the top five. Maybe you think WAR is stupid (I see why). I love that two of the best are playing for the Astros in 2017. Jake might have a shot at toping Spiers in the WAR category before it's all said and done. I'd love to see Marwin stick around longer than Walling.