tedster - 3:52 pm on Jun 9, 2010 (gmt 0)
backdraft7, we had several threads last year that reported traffic throttling and "dayparting" of traffic. I've seen some of the analytics graphs, and there's no doubt that Google has the technology to pull this off. The question is why do some sites get this treatment - only a very few from what I can tell.
The closest I could tell last year is that it was a kind of backlink profile issue. The sites involved (and some were very big brands) had just done "link building campaigns" that were stuck on just a few types of backlinks - in other words, there was something unnatural about the whole profile. This seemed to be a way that Google said "we don't completely trust these backlink signals, even though the business is essentially sound". That's just educated guesswork, and certainly not a definitive analysis.
In every case I know of the condition did go away - in weeks or in one case after about four months.