On one of my phrases that has suffered a drop of 30 to 40 positions in the past 6 months, Google preview is placing the orange box around the entire content area, rather than the exact phrase. This is not happening on any other phrase. There are various topics on the page, so I don't understand why Google would highlight/box in the entire page for "big blue widgets", rather than the exact phrase that appears only once. I wonder if the algorithm is somehow seeing my page incorrectly, thus causing the drop in ranking?
i would try some or all of the following: - fetch as googlebot in GWT - view the cache link for that page in the search results if available - view page with js, styles and images off - Firebug or similar web development tools