aristotle - 7:54 pm on May 4, 2013 (gmt 0)
No, I understood, and as I said it's a good point in theory. What I'm telling you is that there is no noticeable or measurable "weakening" of the rest of the site. With the exception of 2 main keywords everything else is ranking as good or better than pre-penguin.
Shepherd - Some sites may be weakened only slightly. It could depend on the internal linking pattern, for example, or which backlinks were removed or disavowed (if any), or other changes in the algorithm in the meantime, or what happened to other sites competing for the same keyword. Also, It's hard to monitor every long-tail search term that a site ranks for to know if any rankings have changed or not. In addition, the effect of disavowing backlinks may not become apparent until the next Penguin update.
In any case, I've seen other threads in which the OP described how overall traffic had fallen even more after backlinks were removed in response to Penguin, which could possibly indicate that the whole site had been weakened. Yes, you're right that it's only theoretical, but I haven't seen anything that would rule it out.