Not really comparing like with like comparing Ange and Nancy imho. Yes they both came from non-European management backgrounds, but Ange had been successful in a number of teams prior to coming to Celtic, Nancy just once, and most importantly imho, Ange had the pre-season to work with in terms of getting his message across and getting in some new players for his system.
Nancy was parachuted in mid-season, days prior to three very big games, and decided to change what had been a winning formula to impose his own ideas.
Not saying Nancy won't be a success (too early to say one way or t'other at this stage) but I think that was a major gamble by him that's failed and it means he's gotten off to a shaky start. Hopefully he has his head on right for the LC final