I'ts tempting to get worried about how much "green" your pages have, but after seeing the drops after the last update I've totally given up on trying to make any sense of what Google's TBPR has to do with SERPS. It seems to have no relevance at all.

I would only see cause for concern if you get a greyed out TBPR. The interesting thing about a greyed out TBPR is it seems it can happen at any time - not just when an update has happened. Similarly, you can get a "zero" (white TBPR) on a new page when no update has happened which I believe (rightly or wrongly) would indicate your page has "made it" into the index.

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Andy Fletcher, not the famous one.