Although the St. Louis Cardinals may have had some expectations for Aledmys Diaz to eventually develop into a solid contributor at the Major League level when they signed him out of Cuba in 2014 to a four-year, $8 million contract, the first half of the contract was, to put it moderately, rocky. While Diaz performed fairly well in 2014, he was hobbled by a shoulder injury, and in 2015, he had just a 77 wRC+ with AA Springfield when the Cardinals designated him for assignment to make room for Dan Johnson, a 35 year-old, relentlessly average-hitting first baseman who had spent the last decade alternating between MLB and AAA.
In slight defense of the Cardinals front office that exposed Diaz to waivers, that the other 29 teams did not place a claim does suggest that the rest of baseball had a similar opinion about the mediocrity of his prospect status.
But the 2016 first-half performance of Aledmys Diaz will force the Cardinals, a team that even after Diaz had a strong finish to 2015 in Springfield and Memphis still felt compelled to sign Ruben Tejada as insurance when Jhonny Peralta went down with an injury in Spring Training, to reevaluate their long-term vision for the rookie shortstop.
To an extent, the Cardinals have already maneuvered to accommodate the rise of Diaz. Before his injury, Matt Carpenter was moved to second base so that Jhonny Peralta could play third base and Diaz could stay at shortstop. While Diaz initially, to the great dismay of many Cardinals fans, seemed stuck batting eighth in the lineup, he has since moved to the 2nd spot.
It is hard to quantify just how confident the Cardinals are in Aledmys Diaz going forward. Apparently the team believes he is better than Ruben Tejada, and the team believes he is a better option to start games than the 2016 version of Kolten Wong which holds a 75 wRC+ and has been around replacement level in the first half of the season, but that is hardly a ringing endorsement.
When it comes to long-term planning around Aledmys Diaz, the first question which must be asked is if he is somebody worth planning around. Certainly, if his true talent is what he produced in the first half of 2016, he is: prorated to 600 plate appearances, Diaz has been worth 4.3 Wins Above Replacement per Fangraphs, which was eclipsed last season only by Brandon Crawford among MLB shortstops.
Because Aledmys Diaz was a relatively marginal prospect, it would be tempting to dismiss his MLB production as an aberration. And while there may be some run-of-the-mill regression to the mean still in store for Diaz, the underlying numbers suggest that this is not a complete fluke.
Batting average on balls in play is a good place to start when evaluating luck: if a player has an extraordinarily high BABIP, it might be the result of an unsustainable tendency for baseballs to miss defenders, and if a player has a low BABIP, it might indicate that he is getting unlucky. And of the 24 shortstops with 300 or more plate appearances at the All-Star Break, Aledmys Diaz ranks 7th in BABIP.
Although a simplistic approach to BABIP evaluation would suggest he's been lucky, if not in the upper echelon of lucky players, Diaz additionally ranks 8th in percentage of balls which are hard-hit. In addition, Diaz's 13 home runs, a power surge beyond his minor league production, suggest a new dimension to his game that the Cardinals likely had not strongly considered. Again, it's fair to expect regression, but he has shown signs of legitimate big league talent.
As for Diaz's defense, while he is still not an elite fielder, it does appear to be improving. He commits too many errors, yes, and his range is not quite at Andrelton Simmons or Brandon Crawford levels, it is still good enough that a player with his bat will make for an impressive part of a starting lineup.
It is important to be wary of small sample sizes, and to consider only Diaz's 2016 production and not his numbers in Cuba or in the minor leagues would be to look at the world through Cardinals-colored glasses. But it is also important to not be so stubborn and incapable of adaptation so as to become mired in preconceived notions rather than seeing the baseball world for what it is.
ZiPS rest-of-season projections predict that Aledmys Diaz will accumulate an additional 0.9 wins above replacement, a total which seems low but this is more a reflection on the conservative nature of ZiPS than pessimism with regard to Diaz: he ranks 12th among shortstops. He is tied with Didi Gregorius; he's fractionally behind Marcus Semien and Addison Russell; he's fractionally ahead of Zack Cozart and Danny Espinosa.
And just on feel, this is about right. It seems to incorporate and consider both an All-Star first half and a non-prospect pedigree. And as the New York Yankees handle Gregorius, by playing him regularly as he continues to be their best option but not placing too much on him as far as long-term expectations, the Cardinals should handle Diaz in much the same way.
Aledmys Diaz was a non-factor for the first two years of his contract, but in Year Three, he has not only made up for lost time but has justified the entire cost of his contract, and the Cardinals should be delighted to have gotten such a relative bargain. But this surplus value does not mean that the team should be more willing to incur risk moving forward.
There is a certain salary level low enough that extending Diaz would be sensible: a point at which even if Diaz regressed to the point of "bench player at best" that many expected he would become in 2015, it would be fine. But the Cardinals should be in no rush to lock Diaz up. The Cardinals have two late-20s infielders who can fill in at shortstop (Greg Garcia and Jedd Gyorko), four of their preseason top 30 prospects are shortstops by trade (#5 prospect Edmundo Sosa, Juan Herrera, Allen Cordoba, Oscar Mercado), and the team recently used its first draft pick on a shortstop (Delvin Perez). And that's not even to mention that Jhonny Peralta, who may have lost a step but could still probably play at least a passable if not particularly exciting shortstop, is no longer injured.
Cardinals fans should appreciate what Aledmys Diaz has done, though they should remain tempered about what he will do going forward. He probably won't keep this up (very few do), and the Cardinals probably recognize this. And it would be in the organization's best interest to keep its options open regarding Diaz and regarding the shortstop position moving forward at least until it has a clearer idea of what Aledmys Diaz is.