Last offseason, the Cardinals had one major hole on their roster looking ahead to 2015, and they struck quickly to fill this hole, trading Shelby Miller and Tyrell Jenkins to Atlanta for Jason Heyward and Jordan Walden. Because Jason Heyward was only under contract for one season, the success of this trade for the Cardinals would depend on how well Heyward and the team performed in 2015. This trade was a perfect example of a win-now move, and it was made out of necessity, as the Cardinals' long-term outfield plans were dramatically altered by the passing of Oscar Taveras. While the Cardinals certainly wanted to keep Heyward beyond 2015, the trade to bring him to St. Louis was only made with 2015 in mind, and the evaluation of this trade should not change because of Heyward's decision to sign with the Cubs.
If Heyward had come back to the Cardinals at a discount, specifically stating that he wanted to play long-term in a place where he was comfortable, then perhaps we could say, after the fact, that this trade involved more than just 2015. However, this kind of scenario almost never takes place, and it would be foolish of a team like the Cardinals to take this into consideration when making such a trade. While fans want to believe that players are loyal and would be willing to take less money to stay in one city, the reality is that players almost always go where they can make the most money, and there is nothing wrong with that. The Cardinals would have had to pay market value to keep Heyward around, just like any other team.
So now that the 2015 season is over and Heyward has moved on from the Cardinals, I thought now would be a good time to give the Heyward trade one final look. (Yes, I know the Cardinals still have another year of Jordan Walden, but I'm assuming that any value he provides will not dramatically alter the overall evaluation of this trade.)
Heyward was brought in to provide elite production in right field, and he was seen as the last major piece the Cardinals needed to be NL Central favorites again in 2015. Heyward did exactly what he was expected to do and then some, posting a 121 wRC+ and 6.0 fWAR. He posted the second best offensive season of his career by wRC+, and he provided his usual Gold Glove defense and above average baserunning. By fWAR, he was the most valuable player on the 2015 Cardinals, beating Matt Carpenter by nearly a full win.
Heyward was especially important to the 2015 Cardinals because the team almost certainly would not have won the division without him. The Cardinals beat the Pirates by two games and the Cubs by three, so Heyward's six wins above replacement likely made the difference between winning the division and being the second wild card team. Of course, some may argue that the Cardinals' right field situation may not have been replacement level without Heyward. Perhaps there is some truth to this, as no Heyward would have meant more playing time for Stephen Piscotty, Randal Grichuk, Tommy Pham, and Peter Bourjos, who are all better than replacement level players.
However, it is important to keep in mind that Grichuk and Pham missed a considerable amount of time early in the season, while Piscotty needed time at Memphis to work on a more power-oriented swing. Without Heyward, the Cardinals' outfield depth would have been woefully thin, and even when players were healthy, there is no guarantee that they would have produced at the same level with more playing time. This is especially true for Piscotty and Grichuk, who were major BABIP overachievers in 2015.
My point is that Jason Heyward's value to the 2015 Cardinals cannot be overstated. He did exactly what he was brought in to do, and the Cardinals have no reason to be disappointed in him. He may not have contributed to a World Series win, but he helped carry the team to the postseason, which is all they could really ask for given the fluky nature of short series in October. He was actually one of the team's bright spots in their series against the Cubs, hitting .357/.438/.643 with a 198 wRC+ in 16 postseason plate appearances.
There is not much to say about Jordan Walden, the other player the Cardinals received in this trade. He was outstanding for the Cardinals in the little time that he did pitch, giving up one run in 10 1/3 innings with good peripherals. However, his season was ended by a serious shoulder injury, and there is little word yet on whether he will be able to pitch again. Walden's injury does not make or break this trade, as he was only set to provide limited value anyway due to his role as a reliever.
The Braves should also be pleased with how this trade has turned out, as Shelby Miller put together a fine 2015 season (3.45 FIP, 3.4 fWAR) and built up enough value to be traded for a talented package from Arizona which included Ender Inciarte, Dansby Swanson, and Aaron Blair. All indications are that this trade was an extreme overpay by Arizona, but the fact remains that Miller is now a good enough pitcher than an incompetent GM could mistake him for an elite pitcher.
Despite Miller's strong 2015 season, the Cardinals did not make a mistake by trading him to Atlanta, and the fact that Miller just brought back a huge package from Arizona should not change how we evaluate last offseason's trade. A year ago, the Cardinals' starting pitching depth was so strong that Carlos Martinez may not have gotten the chance to start had Miller not been traded. The Cardinals opted to keep Martinez instead of Miller, and after one season, it looks like they made the right choice. Martinez's 3.4 fWAR was identical to that of Miller, but he did so in 25 fewer innings with the peripherals to suggest that he can sustain a low 3's ERA. Miller, on the other hand, posted a 4.07 xFIP and 4.16 SIERA in 2015, and as I pointed out in my piece at Beyond the Box Score a couple weeks back, Miller does not appear to have the skillset needed to outperform his peripherals going forward.
Simply put, the Cardinals traded someone they did not need for someone that they very much needed. Even with his strong 2015 season, Miller would have only been a slight improvement over one of the Cardinals' five starters, Michael Wacha. It is also important to note that Shelby Miller was one of the worst starters in baseball in 2014, when he was barely above replacement level despite pitching 183 innings. There is no guarantee that Miller would have had the same breakout year if he had stayed with the Cardinals, as whatever approach they were using with him in 2014 clearly was not working.
In fact, I would argue that the Cardinals still do not need Shelby Miller, even with Lance Lynn out for all of 2016. Steamer currently projects the Cardinals to have seven starting pitchers (Wainwright, Martinez, Garcia, Wacha, Lyons, Cooney, and Gonzales) with an ERA lower than that of Miller next season. (Steamer projects him for a 4.09 ERA in 187 innings.) This projection may be overly pessimistic, but it reflects the fact that Miller has yet to post peripherals that would suggest that he can prevent runs at an above average rate.
The Cardinals should be satisfied with how the Heyward trade turned out, even with Heyward's departure and Miller's success with the Braves. The Cardinals efficiently allocated their resources by trading from an area of strength to fill a major weakness, and they likely would not have won the division in 2015 had they not made this move. In addition to improving their team for 2015, the Cardinals did not seriously harm their long-term outlook by giving up Miller. They have several pitchers on their major league roster capable of providing a comparable level of run prevention, and they also have strong pitching depth in the minor leagues.
Overall, the Cardinals have little reason to miss Shelby Miller, and they got exactly what they were expecting from Jason Heyward. That sounds like a good trade to me.