Sometimes early voting can tell a story that is different from the obvious?

One of the things I was reading recently was that in Florida, there was record setting early voting and that early voting was especially good in traditional Democratic strongholds such as Broward County.  The intuitive situation is that when a county like Broward (which went 67% to 31% for Clinton over Trump) has big numbers, that this is good for Biden. 

Now, obviously anywhere a candidate is considered a heavy favorite in an area (or county in this case), it is good to have as many voters as possible putting in their early ballots. But does that tell the "whole" story? Is it possible that there could be heavy early voting in a county like Broward, yet not necessarily be something that is "good" for Joe Biden?

If we look at some  Broward county numbers for early voting (this report is from a few days ago) - it shows that there were 13,391 Democratic ballots returned, while there was 8310 Republican ballots returned, and 6516 ballots returned from people not affiliated. Assuming that the vast majority of Party ballots are being returned across Party lines, the Republican ballots already make up approximately 30% of the ballots returned, whereas the Democratic ballots only make up 47% of the returned ballots. 

This essentially makes it effectively impossible for Democrats to be running ahead of their 2016 totals in terms or percentages. Unless nearly every independent ballot is marked for Biden, he is not going to reach the 67% of the early vote that would be reflective of what Clinton received in the full count. On the flip side, it would only take an extremely small percentage of the unaffiliated ballots to have Trump marked, for the President to be running ahead of his 2016 percentage in Broward County. 

So what does this tell us? Well at least in Broward County there is not factual tangible evidence at this time that Democrats are early voting by the same margins as all of the polling suggests that they are. If these polls are correct, we would not just expect more Democrats than Republicans to be voting in Broward county, we would expect that the percentages would be larger for Democrats than they ended up with in 2016 (because there is a much larger number of Democrats in Broward county). If this early voting holds true, and Republicans turn out heavy on election day, then Biden could be looking at a much closer Broward County result than Hillary won. That would be bad news for Biden in Florida where they expect huge percentages and even larger raw numbers out of these counties.

Of course, this could simply mean that more Democrats than expected will vote on election day or that less Republicans than expected will vote on election day. Perhaps someone's intent on "when" to vote is not as important as who they intend to vote for?

Or perhaps the Democrats of Broward county are in "why bother" mode? After all, Biden leads by double digits and the President has all but conceded the election. What incentive or reason do they have to just "pad that total" when they can just sit this one out and still see their candidate win by a landslide?