Royal Rother Possibly.
But I do find it surprising that the most successful manager of all time has had an almost unbroken succession of failures in management from his pupils. It seems like the longer a player was with him, the less likely they are to be successful in management.
And pretty much the same applies to his succession of No 2s.
At the very least I find it odd because I would have expected it to be the other way around.
I think it points more to those who have stellar playing careers not necessarily making the best managers.
Having said that, Hughes, Strachan and Bruce have had almost unbroken managerial careers lasting in excess of 20 years.