Dragon Age 2 was the first poop in the pool, so to speak.
I see people dropping the old Baldur's Gate games as the start of the fall. I'd call bullshit on that, myself. Jade Empire, KotOR, Mass Effect, Dragon Age - all of these were awesome games. Hell, I'd argue that Mass Effect 2 was overall the best ME game (ME1 had a stronger main plot, ME2 had better gameplay and stronger characters).
But Dragon Age 2 was the first time they truly dropped the ball. Too many cut corners, sloppy design and shoddy writing resulted in a "meh" game. It wasn't terrible, it was simply not up to the standard set by the first game and previous Bioware games in general.
TOR was a letdown considering the level of hype and, more importantly, the funds sunk into it. Heck, it's the likely cause of DA2's suckage (resources being shifted to TOR). While DA2 was a failure from a design standpoint, TOR is a failure from a financial one. And the game itself is, again, kinda "meh"...
Now, it's not all gloom and doom. Mass Effect 3 is a genuinely good game, solid on all fronts, right up until the ending. The other major complaints regarding ME3 have been about it's business model (the Day 1 DLC and all that).
All this indicates that Bioware still has talented people who want to make great games, but are being pushed around by EA to the extent that projects don't receive the attention they deserve, resulting in an inferior product (DA2) and good games get saddled with baggage that drags them down (TOR, ME3).
I wish Valve would start buying up major developers from shitty publishers...