What exactly is "a world class manager" anyway?
With the possible exceptions of Jose Mourinho and Louis Van Gaal, I don't think we've ever appointed a manager who, at the time they joined us, would have been considered "world class". Probably the best British manager ever, and the best we ever had, joined us after spells at East Stirling, St Mirren and Aberdeen - hardly the stamping grounds of "world class" managers. Our second best manager hadn't managed anybody at all prior to taking up his post.
The ideal isn't to hire a proven "world class" manager, one who has most likely already started to decline by the time he's appointed, but to find the person who will become "world class".
Is Jurgen Klopp world class? Whether you think he is or not, he would certainly not have been described as such when he was appointed.
Is Pep Guardiola world class? Given his success at three different clubs, you would probably say yes to that. Was he world class at the point he joined City? Perhaps he was, but there was a suspicion that he'd not really been tested at either Barcelona or Bayern given their dominant status in their respective leagues.
Who else out there is world class? How sure are we that their description as such is merited by what they can accomplish in the future rather than what they have achieved in the past? Does being a great manager in, say, La Liga translate into being a great manager in the Premier League?
I'm sure Ole's reign will not be a long one (is anyone's these days?), but I definitely hope his replacement is not based solely on past accomplishments in foreign leagues.