Why D-backs would say no to an A.J. Pollock-Shelby Miller trade

So the Atlanta Braves apparently tried to get A.J. Pollock from the Arizona Diamondbacks for Shelby Miller:

Rosenthal said it wasn't an unreasonable request. Well ...

Pollock 2015 WAR: 7.4

Miller 2015 WAR: 3.6

Pollock 2014 WAR: 3.9

Miller 2014 WAR: 1.6

Pollock 2013 WAR: 3.5

Miller 2013 WAR: 3.4

So actually .. yes, it kind of was a little silly. If the proposal did happen, it shouldn't have taken the Diamondbacks more than a few seconds to hang up. Pollock is the much better player. Both have three years remaining of team control, so that wasn't a factor. The Diamondbacks do need starting pitching, but Pollock has become one of the best all-around players in the game; he was just as good in 2014 but he was injured and played 75 games, so we didn't realize he'd had a breakout season a year ago.

Maybe you don't believe the power spike in 2015 was real, except he's slugged .498 each of the past two seasons. Maybe you think his Gold Glove was a fluke, except his defensive metrics have been excellent in all three of his seasons in the majors. Maybe it 2015 will be his peak season, but he should remain excellent for several years. He's increased his walk rate while cutting his strikeout rate. He catches the ball. He has pop, with 65 extra-base hits. He's absolutely for real.

Miller is a nice pitcher. But there a lot of nice starting pitchers these days. Among qualified National League starters, Miller ranked 12th in ERA, eighth in innings, 15th in batting average allowed, 35th in walk rate and 29th in strikeout rate. He's been durable in his three seasons, is still young and give him credit for remaining mentally strong even though he received such little run support that he went through a 24-start winless streak before finally winning his final start. Don't get me wrong: I like Miller.

Anyway, the trade proposal points to something else: The Braves realize that maybe you actually do need to field a lineup with eight position players. And also that they're not necessarily planning the next potential Braves playoff rotation to be constructed around Miller. They've built a stockpile of pitching prospects, but because the team is unlikely to be competitive until at least 2018, if you do trade Miller, wouldn't you want to trade him for players with more years of team control?

The Braves have already traded Andrelton Simmons. They could be trading Freddie Freeman -- as Buster Olney wrote today, "The Houston Astros have been digging into the market for first basemen, and have checked in with the Braves on the availability" of Freeman. Heck, they might as well start shopping Nick Markakis as well.

All the better to ensure that No. 1 overall pick in the 2017 draft.