A new set of Nielsen findings show that the audience numbers drop pretty dramatically during the commercial breaks of even the top network programs. The new data is drawn from Nielsen's new minute-by-minute ratings tracking. Commercial blocks during such top shows as CSI, American Idol and others all dropped by more than five percent. While that number might not sound huge, it's significant to the advertisers who bought time based on ratings guarantees. Those assurances are given to ad buyers by the networks during the upfront buying season. If the number of people watching the ads is significantly less than the number watching the show then it could mean a revisiting of that process, something the networks are loathe to do. The reality is, though, that advertisers need to get what they pay for and a new set of ratings like this could provide that. Some network execs put the onus on advertisers, saying they need to create better ads that hold the viewer's interest. That's true to but that's fixable and the ad community is working on that to some extent. But the networks also need to realize that if the number of viewers the advertiser is buying doesn't match those watching the ad then there's a problem with the system.