If one site abruptly made significant changes to their link profile, could it trigger a ripple effect that could be felt across many sites?
We recently began making changes to remove some old, bad links that accounted for a unacceptably large percentage of our link profile -- on the order of 65%+ on a profile of nearly 2 million links.
While the change is just recently starting to show up in WMT -- only about 10-15% of them are gone so far -- we had seen some small positive gains in ranks and traffic, which was encouraging. While those gains have leveled off, I am now noticing that a number of other sites in our profile appear to be targeted by Google and have dropped in PR -- PR5's and 6's dropping to 2's and 3's, and 3's and 4's dropping to 0 -- including a couple sites that stopped linking to us over a year ago.
While I can't be absolutely sure on the timing of the PR drop, I do know that the change did not occur prior to the links being removed about a month ago, and I'd have a hard time believing that the timing is coincidental.
Is there any precedent for this behavior?
I've definitely seen it work in the opposite direction, from the top down, but not from the bottom up.