Evers has a lot of similarities to Biden. To a lot of outside observers, he's seen as a boring old non-threatening white guy. But in reality, he's pushing the same policies and keeping right in sync with the national Democratic Party, just like Biden. And people (voters) know this, if a Dem were actually more moderate or less offensive to Republicans and R-leaning independents, it would be noticeable, since the Dems are so uniformly together these days. But even Morning Consult shows Evers less popular than Whitmer or Wolf. Maybe the difference between Evers and Whitmer/Wolf is that he has been handicapped more by the legislature and courts. But Whitmer/Wolf also have an R legislature. People know what Evers would do if he had those two institutions agreeing with him, and it wouldn't be too different from any other Democratic governor.
I think the idea that opposition to Whitmer is based on sexism (that people here apparently believe) is crap, and her kidnapping plot was literally aided by the FBI. But honestly if Evers is seen as having a better chance because he's not as threatening or provoking, then there might be some validity to that.
Sinema is an example of this, as polls have shown that she enjoys higher approval ratings among Republicans than she does among Democrats, and certainly much higher than her colleague Kelly. Republicans view her as a more independent-minded Democrat who doesn't strictly adhere to the party line. They hold this same view of Manchin, with recent polls indicating his approval is as much as 30 points higher in West Virginia than Biden's.