Is Yahoo! Tier II?

Is Yahoo! Search Marketing a second tier PPC search engine, packaged as first tier? With the new ad delivery report, you can judge for yourself:

You probably know that your ads can appear not only on Yahoo, but on partners throughout our distribution network, and that you can block them if they’re not performing for you. But until now, if you didn’t have a pretty good head for web measurement stuff, you probably didn’t know which traffic sources were working for you. Now our Ad Delivery Report will let you see how your ads are performing on various partners, and use that information to block the partners who don’t give you what you need.

Here's an example ad delivery report, sorted by impressions:



I've outlined in red a couple of striking statistics. First, note the ad distribution to 4635 domains. The blocked domains feature has a limit of 500! Second, note that search.yahoo.com did not generate the most impressions. In fact, less than 7% of ad impressions originated from Yahoo! Search. That's what's making me wonder if Yahoo! is packaging second tier searches and selling them at first tier prices.

What do you see in your Yahoo! ad delivery reports?