Well, yes skill(tactical, Tori movement understanding, etc.), but definitely not win ratio.
Many amazing players don't have an amazing win ratio, based on the amount they lost when they were beginning or how many they lose while just playing "for fun" mods with friends.
For sp
Innovative
Knowledgeable about tori
Patient
For mp
Tactical
Strong understanding of player vs. player mechanics
Ability to position oneself and use leverage for fast, strong movements
I'd also add the SP element into MP. Trying to progress with my SP skills have substantially increased my overall MP skill, and it helps a lot with spars etc.
Will ratio is telling how much they win out of all the game that they have played, which is there Qi. If you are talking about how much they win, then it is Ratio.