NASHVILLE, Tenn. -- The Arizona Diamondbacks' past two first-round picks, as well as their sandwich-round pick from 2013, are now property of the Atlanta Braves, and all Arizona will get out of all of that value -- potentially 18 years of major-league service across the three players -- is three years of a good No. 2 starter.

I've long been a Shelby Miller fan, primarily because I loved how his arm worked and the potential for two plus pitches, but it wasn't until late in 2014 that he turned the corner and became an above-average major league starter by adding a sinker and changing the grip on his curveball. The result in 2015 was the best ground-ball rate of his career and a 3.4 WAR season (per FanGraphs), more than he had generated in the two previous seasons combined. That's more than any Arizona pitcher produced in 2015, and second only to new D’back Zack Greinke on their projected 2016 staff. Assuming Rubby De La Rosa goes to the bullpen, where I think he'll thrive as a two-pitch guy, they're probably eight wins better just from the Greinke signing and this trade.

But the cost is comically high. Shortstop Dansby Swanson was the first overall pick in this June's draft; thanks to a rule change this summer, teams can now trade drafted players in the ensuing offseason rather than having to wait until one year past their signing dates, so Swanson can report to Orlando, Florida, in late February rather than going through the charade that surrounded Trea Turner last year.

Swanson is a top 20 prospect in all of baseball, a true shortstop who projects as an above-average or better defender there, with plus running speed and the potential to hit in the .290-.300 range with a handful of homers and good OBP skills. As a product of Vanderbilt, he's very polished, having performed well in the toughest collegiate conference in the country, and he could see the majors at some point in 2016, in the same way that Kyle Schwarber and Michael Conforto reached the majors 12-14 months after they were drafted. Swanson alone for Miller is a great return for Atlanta.

But wait, there's more! Arizona also gave up right-hander Aaron Blair, one of their top two pitching prospects, a major league-ready starter who posted a 3.16 ERA in a half season pitching in Reno, a terrific hitter's park in the hitter-friendly portion of the Pacific Coast League. Blair is a strike-thrower who generates a lot of ground balls and misses just enough bats thanks to a strong three-pitch mix, with heavy sink on his low-90s fastball, a plus changeup, and a much-improved curveball. He might have a slightly limited ceiling, but there's a hint of Brandon Webb in here -- not quite the same ground-ball rate, but still one likely to be near the top of the league. He probably won't produce as much value as Miller in 2016, but that gap should narrow quickly, and I would rather have his next six years than Miller's next three.

Now how much would you pay? Oh, wait, Arizona already paid, and it's even worse than you think. They also gave up Ender Inciarte, a slap-hitting outfielder who is an excellent defender, capable of playing above-average defense in center or plus defense in left. Inciarte never walks but rarely strikes out, and he's very light on power, so most of his offensive value is tied up in his BABIP. He's such a good defender, however, that he's a fringe starter even if he hits an empty .260. By FanGraphs' WAR, he actually produced as much value as Miller did in 2015, although Miller is more of an upgrade for Arizona over what he's replacing than the drop-off from Inciarte to Yasmany Tomas in the third outfield spot. That said, five years of control of Inciarte is worth more than three years of control of Miller, even assuming Inciarte won't hold his 2015 batting average and Miller makes some modest improvements to his control.

To give up Inciarte and two of the team's top three prospects is almost as bad as the deal when the Diamondbacks gave Touki Toussaint to Atlanta last summer to be rid of Bernie Lomax's corpse. They are indeed better, close to playoff contenders at this point, but the long-term cost is just staggering. Atlanta fans should be absolutely giddy; their front office took Jason Heyward's last year under club control and converted that into pitching prospect Tyrell Jenkins plus this giant haul and a good year from Miller on the mound.