2 issues. One is that I think the numbers on the graph like 5 mean the probability of you winning (plus half the probability of you tying) after your turn 5. And for your opponent, the same after THEIR turn 5. So you probably want like half-turn increments instead of the slightly disjoint thing we have, but that might be a bit hard to program in. Further, I think there's either a slight bug or a rounding issue, because I think the reason a probability of 2 is popping up sometimes is because in those cases, the evaluator thinks someone's probability has gone over 1. At least that seems to be the case in the instances I remember.
Finally, I'd like to wonder why it doesn't jump to 1/0 when the game has ended. Probably I'm interpreting stuff wrong.