It is very unlikely for Rafaela to carry the team as compared to yun zhao and Layla. She is mostly played as a support and you can't support stupid. Even if you build her as a carry, her stats and skill set does not compliment well so you end up being neither here nor there.
Also she is very weak in the tier list at the moment. What she can do, other mages can do better than her. Nana slow and stuns are more reliable and she outputs higher magic dps than Rafaela. The healing output of raf is also rather bad in a teamfight that you can't really save anyone from getting bursted by assassins. All you do is get the extra movespeed which most of the time doesn't matter.
If you want to win, either find a good group that can make use of her strengths or just pick another more reliable hero.
