I am paraphrasing here.
https://www.azcentral.com/story/spo...ks-st-louis-cardinals-speculation/1409215001/MLB.com's Richard Justice recently suggested that the Diamondbacks trade Greinke to the St. Louis Cardinals.
He listed it as one of "seven trades that make perfect sense."
He wrote: "We’re going to talk about the D-backs a couple of times here. Arizona is one club that’s definitely in limbo. They aren’t going to catch the Dodgers for the National League West crown, and they don’t seem equipped to stand out in a crowded NL Wild Card race. If they decide to sell, they could be well positioned to take a big leap next year. Greinke could be a postseason difference-maker, but this trade is complicated because of the $35 million he’s owed in 2020 and '21. He’d also have to approve a trade. Here’s guessing he’ll be happy to approve a deal that gets him back in the postseason. As for the money, the D-backs would have to pick up some of it, perhaps in exchange for a sweetened package of prospects."
Justice was pretty vague in his story as to what the Diamondbacks could get in return for Greinke.
As for potential trade pieces, he wrote: "The Cardinals have done a tremendous job building Minor League depth, even with so much of their homegrown talent in the big leagues. The quality of the package would depend entirely on how much money the D-backs were willing to eat, with only third baseman Nolan Gorman (St. Louis’ No. 1 prospect) likely untouchable."