The fivethirtyeight.com forecast in 2016 gave Trump a 28.6% chance of victory. It's predicting 12% for 2020. That's a pretty big difference.
If I told you "there's a 30% chance of rain tomorrow" and it rained, you probably wouldn't accuse me of being wrong (based on that one data point at least).
If I told you "there's a 30% chance of rain tomorrow" and it rained, you probably wouldn't accuse me of being wrong (based on that one data point at least).