Usually it's because as it searches the move tree, it finds ways for the opponent to maximize their own winning probability and so has to hedge against that. In

Usually it's because as it searches the move tree, it finds ways for the opponent to maximize their own winning probability and so has to hedge against that. In minimax games sometimes the evaluator finds a long chain of moves that leads to a win, and once it finds that, doesn't necessarily bother trying to find a shorter one. It can be frustrating to tune that out.