Google's John Mueller said in a Google+ hangout this morning at the 8:09 mark that after you "recover" from a penalty, "it's almost never going to be that we will just restore the previous state" of your rankings you had prior to the penalty.
Why, he said because the web evolves and because of that, things won't be the same. Of course, you and I know that penalty removal does not mean you rank in the same spot you did rank before you had a penalty. Why, well, the signals that you had to rank you originally no longer are benefiting you. But John didn't say that, I think he wanted to though.
Here is the full transcript:
Question:
We lost half of our rankings after an algorithm update (probably Panda), and other sites that copied our content started ranking above us. Will Google restore our rankings (copied pages by others) when we fix the all search quality issues?
Answer:
In general we will try to take that into account. When we see that site make significant changes in the quality of the pages. So that's something where I suspect you'll see positive changes.It’s almost never going to be that we will just restore the previous state because things evolve on the internet, things evolve in our algorithms and any previous state will be different when we look at it now. So even if nothing happened with your website with our algorithms in the meantime the rest of the web will have evolved, so that previous state might be different from the new state that that will come up.
So that's something where sometimes we see this question with regards to short-term changes that sometimes we also see this question with regards to long-term changes. Where it's like three years ago my site was ranking at this position for these queries and I fixed the issues that were involved, will my rank like that again? And obviously especially over a longer period of time like a couple of years that the web will have evolved, things will have changed quite a bit in search.
Here is the video:
Forum discussion at Google+.