The ambivalence to McDonald is due to a couple of factors, I suspect. One, he said he doesn't see eye to eye with the new gaffer. Two, even in a good year he was often not fit until September/Oct - and he's done zero pre-season so far.
Add to that the fact that Robinson is looking for a younger and faster striker, Skippy's ruled out on both counts.
Maybe the fact the turned us down for this season also plays into the feeling.