Just to add some fuel to the fire, we've created a similar site to our big one that's currently pandalized, different content but same structure & within 2 months it's absolutely killing it in the SERPS.
So what's a webmaster to do? Same structure has survived a Panda iteration & is doing well whereas the main site is tanking. Where does Google think we are going to focus our efforts? There's only so much time & money we can put into a site that's showing little to no signs of recovery.