First, the editing isn't as locally precise. For example, it's unlikely a GateHouse sports copy editor in Austin knows much about the high school football teams in another state and may not catch a misidentified player, incorrect conference, etc. This can be offset to a certain extent if there's an editor from the home paper giving copy a thorough first read before it goes to the editing hub, but how many papers have that luxury these days? Perhaps a paper the size of the Oklahoman does; some larger papers that have eliminated their desks have retained a copy editor or two to serve as a liaison with the editing/design hub, but again, it's a luxury.
Second (and obviously I don't see every GateHouse paper, but I'm going by what I've seen and heard), page design is often downright strange. For example, I've yet to see a headline that's size- and story-play appropriate. Huge headlines on downpage stories of secondary importance. Small headlines on lead stories and centerpieces.
Third, headline and cutline quality: I'd rewrite just about every headline I've seen on GateHouse pages, and too many of the cutlines are regurgitations of what wire-service photographers provide without much rewriting or additional information (instead of saying, "The Cubs' Kris Bryant looks on from the dugout," pull some information from the story and tell me why the photo is relevant).
Fourth, early deadlines. For example, I know of an East Coast paper that has outsourced production of its baseball pages to Gatehouse, which operates on its own timetable. The first version of these pages is produced almost two hours before the home paper's first-edition deadline. The first edition at least used to get night games from the Eastern time zone in the paper; now, only day games make it, and there's a ton of filler. And there have been many reader complaints.
I make these observations with all due respect to those who work in the Austin editing hub, which is known to be underpaid and understaffed. No doubt many of those folks could do much better work under different circumstances. I'm probably prejudiced against the place because so many of my hardworking brethren have lost their jobs and quality has suffered, all in the name of saving a few bucks.