Well, back in 2005 the networks were alot stronger than they are now- multichannels and all. Nine still had hits all over their schedule which had been top-rating for years- Seven had several new hits. Today, you don't see the same sort of strength in the Number One Network.
Seven have come from second/third in demo's last season to outright first across all of them (both in primary channel and network stakes). Hardly a sign that there is no strength.
Seven has several decent shows, but it hasn't been able to find a show to replace CSI, it hasn't been able to keep Desperate Housewives over 1 million, its comedies (like HIMYM) are shuffled back to multichannels and Rafters, which was a mega-hit when it first began, has been treated like garbage and as such is shedding viewers. Nine back in its day was a consistant, well-oiled network- today, Seven is the "Steven Bradbury of Network Television." (Cheers, Joe Hockey) It just wins because it has a few shows which beat out the rest- e.g. DWTS, AGT beating 9 and TEN because there is nothing on.
To say Seven wins because the other networks have nothing on is to underplay their strengths, much to say Ten only does well with MasterChef because they advertise it well.
Nine gave 2011 a good shot with sitcoms and new comedy programs, all of which flopped for whatever reason that may be. Seven played up their strengths and launched longer (and more hyped up) seasons of MKR and AGT to massive success. Winners and Losers did brilliantly in the demo's and is more successful than any other new Aussie drama since Rafters in 2008. They cut factual's out of the picture and pushed new 7:30 content. Having a solid 7pm option helped them feed a solid audience into that slot every night, something Nine hasn't managed (apart from The Block).
If Nine plays their cards right, they could have BB stripped 6 or 7 nights a week winning timeslots and putting the network into first place. Furthermore, the lead-in to shows like CSI and POI could help regain some 8:30 stability. It might sound far-fetched, but I remember someone saying on this site (or TVTonight) that "When the TV goes on at 6pm, it usually stays on the same channel the whole night..."
If that is the outcome, Seven will have no chance. Of course, if Nine do muddle things up (which is very likely), it could be a trainwreck.
There's my essay done.
Seven are intelligent enough to push their lower-rated drama's to Thursdays. Nine never learns their lesson with CSI and continue to try and return it to "hit" status when those days are clearly behind it. CSI will never, ever, hit the million mark again. It could sit behind the finale of The Block and still not attract a winning audience.
Person of Interest will suffer from Nine's own stupidity to return CSI to Sundays and kill off the small audience it had gained behind Underbelly.