For quite a while, there has been complaints about parts of the AI of PCM10 - especially after t became known that patch 18.104.22.168 was said to be 'final' and that the problems therefore wouldn't be fixed. On this forum, the problems have been summarized in 'Contador wins the mass sprint!'.
The discussions heated up last week when Cyanide (or what seems to be the moderators) started deleting critical threads and members from the official forum.
However, today, Cyanide published an official statement on the matter, saying that they are now working on a new patch. The problem with non-sprinters winning flat stages have been identified and will be fixed. They are still having problems with identifying problems with gaps in hills/mountain, but they are working on it.
You can help out by uploading replays of the problems. Use the official DB, make sure to enable replays in the options menu, and play the 'bugged' stages. Upload your replay (My Docs/PCM/Replay) somewhere and post the link here. It will then be forwarded to Talleyrand who forwards it to Cyanide.