Not sure where you heard that, but the grass in Lancaster is completely natural, not artificial. Further, the city groundskeepers at The Hangar had been working with the Astros' groundskeepers to make the field better and better over the last couple of seasons - it's just been reseeded as of the end of the season here. It seems to me that blaming a ballpark for inconsistencies is kinda silly considering the number of players in the Majors who have come through Lancaster. You can find the list here: http://www.milb.com/content/page.jsp?ymd=20130201&content_id=41349154&sid=t491&vkey=team5
