Google is making more tweaks to it’s Quality Score Algorithm. They seemingly will normalize the data dependent on the position in order to be “more precise” in serving up the more relevant ad. Positions have a direct effect on CTR. If lower CTR ads found in the lower positions were placed in a higher position, it is entirely possible the new CTR would be better than the current holder of those high placements.

Straight from the horses mouth that is Google.

“Clickthrough rate (CTR) is the most significant component of Quality Score because it directly indicates which ads are most relevant to our searchers. As you probably have observed, ads in high positions typically earn better CTR than those in low positions, because ads in high positions are more visible to searchers. To calculate the most accurate Quality Scores, it’s important that the influence of ad position on CTR be taken into account and removed from the Quality Score.
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