When all these polls showing Trump up big are posted, I think of the old adage, “how do you eat an elephant? One bite at a time.” Anyone expecting an immediate flip in the polls was dreaming. Desantis needs to start taking small bites out of Trump’s poll numbers in the early primary states. If we start seeing a tend toward Desantis beginning to gain on Trump by Independence Day, then he has a chance to make a dent in Trump by January. A strong showing in Iowa and South Carolina could drive the other candidates out of the race, making it a 2 way race between Trump and Desantis. If Trump is tied up in court most of primary season, that could make things really tight. And if Trump is actually convicted, all bets are off. Lots of people who would be willing to vote for Trump are not going to want to risk having a nominee who could be sitting in a jail cell come Election Day.
You could just as easily make an argument that an ex-president polling only in the 50’s is pretty weak.