Saddam could keep people under control to a degree, because he was a dictator (it's easy for them); more importantly, he could repress away for a long time without the 'international community' making a fuss, as he was working for us then. I don't believe for a second that arabs (or anyone) are incapable of democracy or decent government - any individual chance of this ever happening was scuppered by the west so the darkies didn't get together and try to keep the resources they happened to live on (see Nasser/Mossadeq/Lumumba). There's a reason our friends are so often dictators - it's because our elite has a contempt for democracy (see any chomsky or edward bernays)
...
In the first article i posted, it talks about how strange it was that the small number of jihadis could defeat iraq's large forces in mosul; it suggests that there's still an extant network of ex-baathist generals who have now allied themselves with ISIS to fight al-maliki - the army 'melted away' because the officers buggered off. This network and the wider sunni insurgency has been working with the US for some time (see the Seymour Hersh Article from 2007 within that link predicting what's happening now)
This is all part of the old Zbigniew Brezinski grand chessboard strategy as far as i can see (same strategy, just some different tactics).
It doesn't seem like ISIS get their orders
directly from the US, but they might as well have (saudi and qatar are fellow travellers). I wouldn't put anything past the US though after reading about the wonderful petraeus' Salvador Option (you know when we tortured and killed iraqis by the thousand using death squads with the same methods as used in central/south america in the 80s (but largely got away with it this time)).
http://www.theguardian.com/world/2013/mar/06/el-salvador-iraq-police-squads-washington
And don't forget the good old SAS dresing up as muslims and planting bombs in mosques
http://www.theinsider.org/news/article.asp?id=1556.
In fact the so-called sectarian civil war that started in iraq after the invasion could be seen to have been started and maintained by false flag US terrorism to avoid any stability interfering with our hegemony (
golden mosque bombing).