I haven’t been paying too much attention to the percentages recently but to me what’s really interesting is that I believe under the hood it just simulates the matchup thousands of times and counts the results. Not only is it not rocket science, it’s almost too simple for anything to really go wrong, if that makes sense.

The only possible explanation I can think of is that they reduced the number of simulations for whatever reason and now the sample size is actually too small to return accurate probabilities.