"what led to crocop leaving Pride"

Take your pick from
1) More money/fame from the UFC
2) Quicker route to the world title in the UFC
3) Doubts over how soon he would have had a rematch with Fedor what with fedor taking fight in russia. If he gets injured ( his right hand has not been 100% for a while) it would have been pushed back even further. Some have said he was avoiding fedor but I don't believe that for a second
4) Pride's future a bit clouded. Plus they are disorganised what with non title fights, etc