Add another: the team ballooned to New Vegas-size and with that comes a dumbening.
Well, the way I see it, having a massive team can indeed be a problem if there is no good direction or leadership to keep the project organized. T:ToN with its large team of writers is a perfect example of how too many cooks in the kitchen can be a bad thing. It seems like each writer operated in their own fiefdom within the game and wasn't accountable to anyone else, so everything feels disconnected and disjointed, and some writers were clearly far better than others, so there is a very inconsistent quality where you can find brilliance in one character, but then 10 ft away run into garbage. There was no clear leader or vision on that game, and didn't people come and go over the course of development? A lot of people around here like to blame Fargo and say he's a crook and pocketed the money or whatever, but there's a saying called Hanlon's Razor which says "never attribute to malice that which can be explained by stupidity". With the disordered and ad hoc development history T:ToN had, it's no surprise the final product is the way it is. There's no reason to resort to conspiracy theories about Fargo being a crook. Inept? Sure.
Deadfire is nothing like that, though. It is very clear here who is leading the project (Josh Sawyer), and he has proven himself to be more than capable as a project director in the past (POE1, New Vegas, etc.) So despite the huge team I'm sure it will be okay. You mentioned New Vegas yourself - that turned out good, didn't it? Dealing with a New Vegas-sized team is something he's done before and it worked out in the end.
The only thing to be concerned about is a lot of this team is probably greenhorns with little or no experience. It has to be this way because so much of Obsidian's talent has been bled out over the years. You can't rely on old talent forever. These raw recruits were hired to fill in the void left by Chris Avellone, George Ziets, John Gonzalez, etc. But everyone has to start off somewhere... we may not know the names of these people because they haven't made one for themselves yet, but in the late 90s who knew the name of Chris Avellone or Josh Sawyer? Back then they were the greenhorns. So please have a little faith, because a decade from now you'll hear the names of some great game developers, and you will look back and remember that it was in the development of
Pillars of Eternity II: Deadfire that their careers first began. Right at this very moment, CRPG history is being made.