Consider the sentence “What is the probability of Bob winning?”
What is the function of “Bob winning”? It’s certainly acting as the object of the preposition, but I don’t recognize this type of construction from any of my English courses. Is it even correct usage?
Some call it the “fused participle” because the participle “winning” is fused with the preceding noun, “Bob”. I’ve heard a few people say it is improper, and that you should fix it to say “What is the probability of Bob’s winning?” “Winning” is clearly a gerund in that case.
However, I don’t see a problem with the construction as the way you have it. To me, I see “Bob winning” as indeed one thing, but it’s easy to look at “winning” as an object complement for “Bob”.