Yeah, I think Melbourn are the sort of team unable to overcome adversity. Or even just endure the adversity. Their first few games it was only after having a significant advantage for a while that they then click into gear. These easy wins gave them a lot of confidence. Then come the Waratahs and they are confident for the first half, but things start to no go their way and look what happens, they fall to shit.
Same thing with the Hurricanes -- that Waratahs game was just an anomaly, they carry that confidence into the game, then the Hurricanes don't just fall away like the Sunwolves did. Instead they get better as the game wears on, accordingly the team then starts to worry if they are good enough etc.
The Rebels will probably beat teams they are clearly better than, but at the first sign of adversity they fold like a fifty dollar note.