Yeah, I heard on a broadcast early in the season, may have been Opening Day, that something like 39 of their first 48 games or something like that were against teams that finished .500 or better last year. Just checked: 3 games with the Pads (.477) and 6 with the Rangers (.414) are it until you get to game 49, May 29th.
That being said, every game this year has been against a team that is currently under .500. (of course, the Astros had something to do with them being under .500).
Right, so much can change year-to-year, but until you get 2 months or so into the season it's just about the best datapoint you can use to sort of determine strengh of schedule.
Going into the season, the Astros had the most difficult strength of schedule in the league over April and May (when factoring in last year's standings).