(Note: Any March or October games have been combined with April and September, respectively)
So out of 19 calendar months of baseball (with a few Marches and Octobers in there), the Astros' 9-19 April 2014 record actually ranks tied for 9th. The .639 OPS is 17th out of 19, which means, that, in the last 3+ seasons of rebuilding, this month was among the worst offensively (it was also offensive, but I'm not into cheap laughs). The ERA, for all its faults, is the 7th-worst in a calendar month - but this is largely based on the 5.86 ERA/1.67 WHIP for the Goatpen.
Depressingly enough, the last time the Astros were over .500 in a calendar month was August 2010, when they went 17-12 on the strength of a 3.21 ERA/1.20 WHIP for the entire month and Geoff Blum had an .878 OPS in 37 PAs.
But let's keep in mind that the Astros have played the Yankees, Angels, Blue Jays, Rangers, Royals, A's (twice), Mariners, and Nationals. Six of those teams (or 22 of 28 games) have greater than a 30% chance of going to the playoffs. Sixteen of their 28 games have come against teams with greater than a 47% chance of going to the playoffs. Of course, the Astros playing them have boosted their playoff odds, and while the Astros aren't going to be favored to win many (any?) games this season, there are still opportunities to pick up wins.