One of the other steps involved in this switch will be getting rid of the “Serve on search only below search results” option which forces ads to appear in specific positions.

Sometimes advertisers get the idea that impressions in premium placement are beyond their budget. They then make the seemingly logical conclusion that they can save money by limiting their ads to those impressions just below search results. The problem, however, is that too many advertisers make the same decision, and increase the competition where there previously was far less. At times, first place in guaranteed placement ends up being more expensive than premium placement. These advertisers end up running the risk of overpaying, while also getting fewer impressions than the users who didn't limit themselves to one ad block.

Getting rid of the “Serve on search only below search results” option will fix this problem: the fewer clicks any specific ad block brings on average, the cheaper these clicks will be. The opposite is also true: raising bids makes it possible for your ads to appear in more noticeable ad blocks and get more of the clicks you want. If your bids are already high enough to make it into premium placement, why deprive yourself of the additional attention in more prominent ad blocks, especially if it leads to more sales and customers?