Democrats likely had just as reliable internal polling as the Trump team. We know this because of Biden's rush to hold rallies in supposedly-safe states.

I wouldn't be surprised if the software was set up to read the vote tally and convert a specific percentage of Trump casts to Biden ones.

Keep an eye on out the 14% number in other counties. If its consistently 14-16%, they had polling suggesting about a 10ish pt advantage to Trump.