Paul Goldschmidt is heading from the desert Southwest to the Gateway to the West.On Wednesday, the Cardinals acquired the All-Star first baseman in exchange for catcher Carson Kelly, pitcher Luke Weaver, infielder Andy Young and a Compensation Round B selection in the 2019 MLB Draft. MORE: MLB hot stove tracker — See who goes whereThis is about as good and even a trade as it gets for both sides. Let’s break it down:Cardinals: AIt’s hard to debate that the Cards did anything wrong in this deal. Goldschmidt, 31, is a bona fide star whose dominance has gone largely unnoticed by casual fans. His career per-162-game averages in the primary offensive categories: .297/.398/.532, 31 home runs, 105 RBIs, 145 OPS+. That’s stupid, stupid good. He was also a good soldier for a franchise that has yet to figure out whether it’s coming or going. The D-backs contended in the NL West for most of the 2018 season before collapsing late, and now it’s looking to pare its payroll, starting with the slugger who will be in his walk year in 2019.Look at the pieces Cards gave up: Carson Kelly, a catcher blocked by St. Louis legend Yadier Molina; right-hander Luke Weaver, who lost his spot in the rotation last season; and minor league infielder Andy Young, who was blocked at second base by Kolten Wong. None of those guys were in the Cardinals’ future plans — their core and future are pretty much set — so they dealt from positions of strength, which is almost always what teams should want to do in trades, no?MORE: Nats going in on rotation again with Patrick CorbinDiamondbacks: B+Arizona is a confusing team. Good talent has routinely taken the field — just look at some of the players it has traded or moved on from: Goldschmidt, Patrick Corbin, A.J. Pollock, Jean Segura, Mitch Haniger, Adam Eaton, Didi Gregorius, Justin Upton and Max Scherzer. Zack Greinke could soon find himself on this list, as well, a few years after signing a six-year, $206.5 million deal with the franchise.While it has been difficult to know whether Arizona is serious about contending, this trade is a step in the right direction for the franchise.Playing the “Will they or won’t they?” game all season would have been less than optimal for the confusing Snakes, so moving Goldschmidt now makes a lot of sense. The organization couldn’t fool itself into thinking it might be good enough to compete for a wild-card spot in 2019 and hold on to Goldschmidt, and then have him walk away for nothing after the season. The truth is, this is probably the most Arizona was going to get for him: a young pitcher, a young catcher and an infielder who has questions but is on the upswing. The D-backs also picked up a draft pick as a sweetener. Arizona does lose points for 1.) Trading one of the best players in all of baseball and 2.) Not getting a can’t-miss-type player back, but the truth is, it’s better to get volume as opposed to just one pla in exchange for a 31-year-old on a one-year deal. Volume is what Arizona got, which makes the return difficult to debate.Overall: A-This trade works out for everyone. Goldschmidt ends up in a baseball town where people will love him, and he’ll get the spotlight he deserves. The Diamondbacks signal a potential new direction for the franchise as they pick up two prospects and a work-in-progress pitcher.The Cardinals are ready to challenge for the NL Central in 2019 while the Diamondbacks have taken their first step toward potentially tearing down the roster and starting anew.