I don't think it matters that 5 Ulster teams have fallen to non Ulster teams, just look at those teams and how they lost.
Fermanagh lost to Laois, this was widely expected. Antrim lost to Limerick in Limerick, not a huge shock as they were playing a similar level team away from home. Down lost to Kildare, Down losing this game was not a shock, perhaps the nature of the loss at home was more concerning. Cavan lost to Roscommon, not a huge shock in that a weaker looking Cavan lost to a strong Ros team. However the score was shocking.
Derry lost to Longford. SHOCK!! Yes this was a shock, perhaps the only real shock when it came to an Ulster side exiting the Championship. Derry had hopes of an Ulster title, and losing at home to Donegal in match with a huge publicity build up was a major blow to the team. O'Boyle left for the States, and they just found it tought to pick themselves up. In saying that they narrowly lost to Longford, In a game they were always going to struggle to pick themselves up for. Make no mistake though, Derry at full strength would lamp most teams in the lower leagues.
Apart from Derry losing to Longford, there are no major shocks here.