Okay, I got another way of looking at this that I think might show you what the hell I'm talking about. We all think StarCraft is a good game, right? A great game even? A game made when Blizzard was at its pinnacle, right? Okay, lets look at the core team and see who did what, according to the credits. Lets start with those guys who left Blizzard.
Bill Roper- Producer, "Manual Design and Layout"
Mike O'Brian- Programming, Battle.net Programming, Strike Team
Patrick Wyatt- Programming, Strike Team
James Phinney- Producer, Senior Designer, "Script and Story", Scenerio Design, Strike Team
Jeff Strain- Campaign Editor (I wouldn't even consider this guy part of the "core team")
Looks pretty bad; the game lost two of it's producers, one of it's senior designer, two programmers (One of whom was working on B.net), the guy who made the campaign editor and three members of the SC strike team (The Strike Team, of course, is the team that ultimatly decides upon whether or not the direction of the game is what it should be.)
Looks like a big hit, doesn't it. (Heh, I didn't realize James Phinney was on that list as well. He must have joined Arenenet later, which is why he's listed so far down the page, not up with the founders. His loss makes things look a bit worse.) However, lets look at the rest of Blizzard's core team who are still working there.
Allen Adhem-Executive Producer, Strike Team
Mike Morhaime- Producer, Programming, Strike Team
Chris Metzen- Senior Designer, "Script and Story", Scenerio Design, "Manual Design and Layout", Manual Artwork, Strike Team
Bob Fitch- Lead Programmer, AI Programming, Strike Team
Samwise Didier- Art Director, Artwork, Manual Artwork, Strike Team
Glenn Stafford- Audio Producer, Music, Sound Design, "Voice Production, Direction and Casting"
Matt Samia- Director of Blizzard Film, Cinimatic director, Cinematic 3D Artist, Storyboard Artist
Ultimatly, those who left ammount to less than half of the original SC coreteam. Blizzard still has the Executive Producter(One of the original founders to boot), the Lead Programmer, the Art Director, the Audio Producer and the Cinimatic Director. Not to mention Metzen (Jeeze; did the guy ever sleep?) who was one of the senior designers, and Mike Morhaime, one of the other producers and original founders of Blizzard. And look, five of the original eight strike team members.
Sure, Blizzard has lost people over the years (I dare you to show me one company who hasn't), however, to say that those people were solely responsible for Blizzard game's being the quality they are is a disservice to the people they worked with.