No it's not the same site.
I'm of the philosophy of "if it aint broke... don't fix it!" However, when it comes to an ever mutating algo... you might be right. Even if it hasn't been broke for years, G may have changed some variable in the last update. I'm a little scared to mess with it though... what if G isnt done updating? It has been nice to have 100k pages indexed and the traffic that came with that.
UPDATE: yesterday my site was back on G again with 111K pages.... this morning its back down to 21 pages.