The Cardinals, I imagine, would disagree with your definition of meaningful upgrades.
Their best signing last year was Miles Mikolas, and it was shredded by the fanbase as a buy-low move for a guy who could not cut it in the majors.
Some times a move made that does not earn "meaningful upgrade" status turns out to be a rather meaningful one after all.
And sometimes meaningful ones flop, like Fowler in 2018.
The Cubs have three nine-figure contracts on their books. One is Jon Lester. The other two are Yu Darvish and Jason Heyward.
Big deals come with big risks.
It's OK to call for them, but don't minimize the risk.
It's not just about losing money. It's about putting the team in a jam. The Cardinals are stuck with Fowler because no one will take on his contract. Imagine if he was owed even more. That's Darvish in Chicago at this point.
Again, I see the Harper appeal and would applaud the Cardinals for going for it.
But if they did, and it flopped, how many would forget they had called for it?