Yuumi + stopwatch

A lot of people hate yuumi, others completely adore her. She has a really bad winrate, but still feels like the most powerful support to fight against. I propose one measure to weaken her by using an example from an earlier game. Midlane fizz and the support yuumi we're premade, while the midlanes we're semi equal and fizz did not get a lead, after teamfighting started yuumi just attahed to fizz, who went on to steamroll the entire game. Fizz can jump on his pole, so 2 enemy champions miss all the cc, fizz also uses stopwatch and zhonya's... so fizz uses stopwatch all the while yuumi keeps healing him. This combo is unbelievably strong... I honestly believe that when a champion becomes untargetable, that yuumi should be forced to detach, same with stopwatch. Give her this weakness and perhaps further nerfs would not have to be considered.