OK so after the last few rounds of Google Algo I've had many sites hit and were dropped from their top rankings. But, a few of these sites have just disappeared from the SERPs all together for their main keywords. I can't find them in the first 20 pages at all. They are all still indexed since they come up when I do a "site:mydomain". These sites are all 3+ years old so it's no temporary dance since they are not new. So what is the best strategy here to get them back again ranking some where in the SERPs? Are they in some supplemental listing or what? Or is this the real sandbox that people talk about. These few sites have disappeared for like the last 1.5 months. Is it still just doing more backlinks and adding content to get them back? Any suggestions?