Odds were on Patti, for all the reasons noted above. And I would add, she was also praised for being a performance as truly part of an ensemble - not necessarily a huge star turn like one would expect from a performer making their return to the Broadway musical stage after 27 years.
But she wasn't a lock; there were some who predicted LaChanze. THE COLOR PURPLE was nominated for quite a few awards and there was a feeling it should get something. And as said above, LaChanze is a veteran performer with years of goodwill from the community. If anything, she wasn't a lock because Celie seemed to disappear in that production.
Sutton, at that point, was slowly becoming perceived as the dependable, always-incredible star we know today. So, few were betting on her.