improved statistics should help small publishers whose traffic converts by attracting more advertisers to the network and making those small publishers stand out from the crowd.
By making specific sites visible to advertisers, it becomes feasible for advertisers to run ads where they want to, and not run them where they don't want to.
Any high quality site which is tightly focused on a specific niche should benefit, once the new tools are available -- including sites that don't necessarily have high conversion rates, if they have high quality content that provides a good environment for building brand awareness.
The losers will be sites with poorly converting traffic, as well as sites that don't provide a desirable media environment for advertisers.
All of this may be a little painful for some publishers in the short run, but it is going to be good news for publishers who already meet the above criteria, or who work hard at adapting to the new environment.