It can be a pain if you're very far down in ranked and hit a wall. For instance, on my server, I am currently ranked at 5th place. However, if you're worried about this you can do what I do, during Sakura's Gift. When I see this event coming up, I remove all ninja from my ranked teams, save for my main, and then do 1 ranked fight, to allow others to fight my new team.

If nothing else, your merged server rank will likely go up, as people beat you, allowing you to face easier opponents, and climb again for the event. Also, in general I tend to focus on my single server rank, and keep my merged server relatively high, so I can have easy wins, if I need them.