As Facebook prepares for its IPO, here's seven reasons why Zynga is in trouble:

1. If you back out Draw Something's 9 million Facebook connected users, then Zynga's daily user count is under 50 million. That's a drop of 18 percent year-over-year.

2. Zynga has no plan to trigger sustainable organic growth.

3. The last break out hit Zynga built from the ground up was CityVille, which now has 6 million daily Facebook-connected players.

4. Since then, it's launched games like Zynga Slingo, CastleVille, and Scramble With Friends — all of which haven't captured the same juice CityVille, or even Zynga Poker, had.

5. ZNGA stock has fallen from a high of $16 to less than $8.

6. Zynga's two most successful games right now are mobile games -- Words with Friends and Draw Something. Both of them were acquisitions. Both are fading.

7. Online gambling is still not legal, so they can't play that card, either.

The good news is that Angry Birds was Rovio's 52nd game so maybe if they keep iterating they'll come up with a winner.

I wouldn't bet on it, though.

Rovio's "problem" was that they stubbornly stuck to their core competency, which is making original games... and almost went under for it, until they got their one big hit. Zynga's core competency is cross-marketing games that they acquire and/or cookie-cutter... but that's mathematically impossible to grow indefinitely.

Kim-Mai Cutler says Zynga has its work cut out for it, because with a market cap of $5 billion it is still aggressively priced: http://techcrunch.com/2012/05/09/was-zyngas-deal-to-buy-omgpop-that-disastrous-heres-some-perspective/