i could give you this video as an answer:
http://www.youtube.com/watch?v=eDBAWHX7a8s
Now we can argue about whether ranieri "defends" our management or not, but if we believe this video then he clearly says that he HAD THE CHOICE, and he CLEARLY CHOSE poulsen. Not a question of money, not a question of secco or anyone screwing up.
As for the point you brought up, i think the players you mentionned are more similar then we all think. Flamini and Poulsen are similar, even if Flamini may be more of a 'constructive' mid then poulsen is. And Alonso on the other hand, is similar to flamini, maybe even another bit more contructive. It's obvious that Poulsen is the more destructive out of all, but in the end, they cover more or less the same spot on the field, that's undeniable. I think that the failing of tiago maybe was kind of a draw-back for alonso. I won't ever compare the two players, but as for positioning and behaviour, there are similarities. And when Tiago got out of our game, it was actually the DM position which looked best (sissoko and Zanetti also) so the reasons why we chose poulsen are not that irrational...
As for stankovic, i think he was more of a backup-option if one of Nedved, Sissoko or Zanetti should be out. I don't think that stankovic was a real alternative to our CM/DM-signing.