There’s no good money to sink into pitching right now, at least not on the free agency market. There’s been some chatter between Miami and Minnesota on a pitching for bats deal - Rosario and Cave were the names mentioned in exchange for Smith, Urena or Lopez. But that seems less likely now that Miami signed Dickerson.
Anyway, if the Twins sense a chance to upgrade, why not take it? If you can’t strengthen a weakness, strengthen a strength. It’s still strength. Their window is wide open right now. Landing Donaldson would allow them to move Sano over to 1B, where he’s better off. That allows them to move Martin Gonzalez to 2B or back to his Houston super-utility role. And Donaldson is excellent defensively, so that’s a net win in itself.
5-7 WAR players don’t grow on trees, and other than an injured free agent walk year, that’s basically what Donaldson has been for the last half-decade on both sides of the ball at a challenging position. Great player, and good-glove, athletic, power-hitting 3B have aged well in the past. Look at Adrian Beltre. Something like 3/$70 would be ideal, but stretching to 4/$90 isn’t bad. If he regresses to a 3-WAR player by years 3-4, you still win on the market math, and you have the best chance to win big when Cleveland is down and Chicago’s not yet reached its peak.