It's on both of them. Ankiel has to call it, and Bernadina should be aware of where his CF is. Since Ankiel's responsibility was easier (yelling "Mine" vs. tracking the ball and trying to watch for another player at the same time), I'd give him a bit more of the blame.
Aren't corner outfielders taught to go get the ball until the CF calls them off? Bernie looked a little reckless, there, but I think this one falls on Ankiel for not taking charge, though he may not have seen the bolt of lightning that was Bernie come shooting out of LF, so there's that, too.
