The game industry average for developers is ~5 years in the same company. It's not a EA thing. You just do not ear about it because most developers aren't public on Twitter.
Important developers leaving a gaming studio is just an issue when it is BioWare, nobody claims it's the end of the world when it happens at Blizzard or Ubisoft.
There was actually a lots of departure in the last 6 months though, but that was people on DA4 which was rebooted and also the super low moral at BioWare following the crap people are saying about their games (from DA2 to Anthem, yes Anthem, game isn't even released and people are already saying it's going to be shit), the company and "their agenda".