Pringle and Vermijl you're probably right, but I wouldn't write O'Connor off after just one appearance. I suspect he will get a loan in January when Cunningham returns, then we can see how he does with regular football in England.
As for Boyle, when he next gets a chance he has to take it, because so far his chances have been sparse but when they have come he's been pretty ordinary. If he doesn't impress next time, with Clarke returning in January, he could find himself as the 5th choice for 2 central defensive spots.
Personally I think he looks to quiet and 'nice' as a centre back, he needs to be more dominant and aggressive.