Eh, I don't think Baldwin is an unbeatable titan, but Hovde is a pretty obvious carpet-bagger and Baldwin has a pro-Wisconsin brand around many corners of the state.
This is the same Baldwin who defeated a popular former governor in 2012 by 6%, and 11% in 2018 (an election with 61% turnout, mind you). With those numbers, Hovde would have to flip a large number of voters just to get to 3%. I don't see that happening, I think Baldwin wins by 6-10 regardless of the Presidential margin.
Slotkin 2-8 seems reasonable, probably ends up closer to the higher end of that.
It wasn't obvious at that time, but over the next 6 to 8 years it quickly became obvious that once a governor has been out of office for some time, their appeal on the voters begins to wane. See also: Ted Strickland, Evan Bayh (who was also a former Senator), Phil Bredesen.
To be fair, unlike those three candidates who were destroyed by their states lean and also just running a bad campaign in Strickland's case, Thompson lost in large part, because Obama carried Wisconsin substantially in 2012. Baldwin actually ran pretty much even with him, only falling short of a point.