[thejeff]

In theory, yes. If it's warping the game that badly.

In practice though, I suspect the damage would already be done by the time it was apparent the situation was that bad. And I really wouldn't want to force someone out if if wasn't really blatant.
In your example, losing half your size/power in 10 turns really only means you're losing the war, not that you're incompetent. I've seen players who'd been doing well all game get taken down much more quickly by a well-executed attack.

And then you've got the problem of finding a good player to take over a probably doomed position.

Edit: So in practice, I suspect it would never actually be appropriate/workable.