This is a terrific trade for the Braves but I think the criticism of this trade has gotten a little hyperbolic. This isn't one of the worst trades in the history of the game or anything like that. In fact, the reasoning on the part of the D-Backs is pretty good.
Arizona is seeing a championship window open. They have Goldschmidt entering his prime. They have Pollock under control for a couple more years. They just signed Grienke. And their offense overall is one of the best in the game. When you add Miller to slide into the rotation after Grienke, you can shift Corbin, De La Rosa, and Ray all down a slot. That improves every one of those spots. Their staff has gone suddenly from shaky to a strength of their team. Pair it with their offense and they're going to win a lot of games.
They're swimming in outfielders out there so they can easily handle the hit of losing Inciarte. They can slide Tomas in fairly seamlessly there.
Losing Blair thins their starting pitching depth a little but he was a good bet to start the year in AAA and, barring injury, wasn't going to have a spot.
Miller also has some ceiling left. He might settle in as an excellent number 2 starter but if that cutter stays as nasty as it was last year and he can refine his arsenal at all, he could be really special. He's still young.
But here's the most important thing. They now have Miller under control for 3 years at a bargain price. Look at the contract Samardzija got. $90 million over 5 years for a 30 year old. Shelby is a good bet to be a better pitcher over the next three years and by a not insignificant amount. Getting Miller's production at his price gives them great financial flexibility.
This is a move that makes their major league team much better. Yes they gave up a huge amount of talent to get him but there is a logic to it for them. I don't think Fernandez was a legitimate option and there wasn't really anyone else that would give you Miller's production at his price.
It was a clear overpay but one that will be clearly worth if if the D-Backs can mount a deep playoff run.