Of course there's the law of diminishing returns; adding more coders to a project isn't a silver bullet, as the new coders have to get up to speed with the codebase before they can even begin to be functional with it. That could take a month by itself for each coder.
And I'm curious as to how you came to your conclusions about EA Tiburon's hiring policies; how much interaction have you ever had with the company to ever get a bead on this?