I don't really think Mills is to blame for the way things are going so far. But, he will probably get axed anyway.
First, we are young. Real young. Second, the schedule has been tough.
The Astros have been playing the Rangers, Cardinals, White Sox, Dodgers, Giants, all hot teams or really good offensive teams. The schedule will play in favor of the Astros more as the season goes on.
I predict from this point forward in the season the Astros will play .500 ball. Being under .500 right now will keep them under .500 for the season, but I think they will play better and better as the season progresses.