I,for one, do not bemoan the departure of Mr O'Connor for one moment. IMHO he was the wrong man for the job under our political system. Unlike the US system in which members of Cabinet do not need to hold elected office, but can be selected from appropriate civilian expertise fields (or election contribution sources, however you want to look at it...), our Ministers must be politicians first. They must be politically savvy and have credibility with the PM. The success of their Depts will rise and fall based largely on that and their ability to work the party power machine in the Battle of the Ministries. Whether or not they actually know anything about Fishery, or Trade, or Defence is really secondary.
Mr O'Connor was, to put it mildly, an inept politician on the national stage. He was, IMHO, a perfect example of "be careful what you wish for": for years we all sat around the mess moaning about not having an MND with any military experience. Well-we finally got one. Too bad his experience was years out of date, and his conceptions (if they were actually his...) for a National Defense Policy were seemingly quite out of step with those of the CDS. He was (again IMHO) utterly lost in the political lion-pit and constantly appeared ill-informed on the issues of the day thus undermining the GoC, and by extension the CF. I usually cringed in anticipation each time he rose to speak in the House, wondering what PR disaster we would stumble into next. Given the PM's extreme concern over tightly controlled imaging and message, I am pretty sure I was not alone...
It is a very debatable point IMHO as to just how much of the recent procurement and reinforcement of the CF had anything to do with Mr O'Connor at all (except as a figurehead); how much was Tory strategy developed prior to the election as part of Harper's overall vision; and how much was already underway or on the books under Minister Graham and the Liberals, with whom Gen Hillier appears to have enjoyed an equaly good if not superior relationship. In my view Mr Graham was a far better and much more respected Minister.
Mr Mackay cannot do worse, and one hopes that he will do much better.
Cheers