I believe in Aledmys Diaz

Aledmys Diaz was historically good in 2016. Just a few data points:

• Diaz's 132 wRC+ was the highest in history for a Cardinals shortstop not named Rogers Hornsby.
• Diaz and Corey Seager are the only two shortstops to post an OPS+ of 133 or above in their rookie seasons.
• Since 1950, only 14 shortstops under 25 have posted a 133 OPS+ or higher, among them Alex Rodriguez, Cal Ripken and Ernie Banks.

As I discussed with John and Heather on the VEB podcast, these numbers were among the reasons Diaz was my 2016 Cardinals MVP. But wherever you rank him, we're all on the same page that he was outstanding in 2016.

So the question is, what should we expect in 2017?

As a Man of Science, I must concede the range of possible outcomes is wide. Diaz outperformed by a good distance even his most optimistic projections, and in many areas was better than his minor league track record would suggest. Those are reasons to worry you are looking at an outlier season.

That being said, while I'm not particularly religious, in this case I must confess: I have faith in Aledmys Diaz.

As suggested by the stats I quoted above, Diaz' offensive numbers were so high up in the stratosphere, you cannot find players who debuted at that level and were just a fluke. On the high-end you have Hall of Famers, but on the low end, you're looking at guys like Jim Fregosi and Travis Fryman, who played 10+ years and posted career WARs in the 25-30 range. Even the low-end among his comparables were outstanding ballplayers.

While it's just a single season, so small sample size warnings abound, Diaz was remarkably consistent throughout. His April was a bit freakish, with a 215 wRC+ inflated by a .414 BABIP. Then there was that stretch in May when it looked like maybe pitchers had figured him out and he struggled - though he still posted a respectable 91 wRC+ for the month. His splits for the remainder of the season are remarkably consistent, and his .312 BABIP on the season shouldn't trigger any asterisks for batted-ball luck.

On the anecdotal side, I was quite impressed with what Diaz did in May, demonstrating what I called the adjustment tool. Pitchers began pounding Diaz low-and-away, and he rolled over those balls. But within the span of just a few weeks, his approach noticeably changed. He let many of those pitches go, raising his walk rate, and showed more of an ability to hit balls the other way.

The fact that Diaz has shown some ability to adjust gives me confidence that he can sustain his performance in a way that players like Matt Adams and Randall Grichuk have struggled to do.

I've focused on his elite offense, but there is still some question about Diaz's defense. We aren't supposed to consider single season defensive metrics, but Diaz's were average-ish, though admittedly a tick below. To my eye, that seems about right, and I would expect him to be an average to slightly below average defender going forward.

If he can sustain anything like his offensive output in 2016, that's good enough for Diaz to remain the Cardinals everyday shortstop for a long time.

Developing players internally is important anywhere, but that is doubly-true at up-the-middle positions. Just look at the Cardinals center field situation. Grichuk was exciting as a potential center fielder. But now that he's seemingly slipping off to a corner position, his bat no longer shines as brightly. And look at where it potentially leaves the team: Shopping for mediocre 30+ center fielders on the free agent market.

In the Alternate Universe where there is no Aledmys Diaz, the Cardinals are in a rough spot this offseason. They are coming off a year where Ruben Tejada took the majority of their PAs at shortstop, and they are preparing a massive free agent bid for Erick Aybar or Darwin Barney.

The Cardinals best hitter is going to be 31-years-old and probably should only be playing 1st base from now on. Their all-time-great catcher, despite a bounce-back season, is in the twilight of his career. While the St. Louis Baseball Club doesn't really use the "rebuilding" word, there is going to be a fair amount of transition on the position player side over the next few years. Aledmys Diaz should be one of the primary pieces the team builds around.