I do not understand this logic whatsoever. If you're a rebuilding team like Arizona, Upton would be the first guy I'd build around. Young, high ceiling, relatively cheap long-term contract extension given that he might become.
If someone offers them a baseball equivalent of Herschel Walker where you get a top of the rotation pitcher, a high level position player and a solid bullpen piece or back of the rotation starter, you have to at least look at it. Royals offer them Greinke plus something else, hey, it is a possibility. Odds of it happening are probably low single digits though.
Somehow seems fit that the two leading wildcarders 20 years after 1984 are the Cubs and the vile Padres. And I get to sit and watch Prior pitch spineless baseball in the first game of the crucial series...gaaah!