To my knowledge there hasn't been much involvement in AI Fantasy Football. However, I would imagine that existing AIs perform fairly poorly. They could probably beat your average player, but not a seasoned football fan who religiously follows the entire league.

I could be wrong though. If there are any examples of AIs performing well at Fantasy Football I'd love to see them!

Personally, I''m waiting for an AI that can outperform experts in Fantasy Football.

No small feat either. The sheer amount of data that needs to be processed is tremendous (think about all of the physical possibilities across all the football teams/games). Humans have the benefit of heuristics. Chess and Go are one thing. But being able to draft a winning fantasy team is a lot harder than it seems.