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It keeps getting worse for Aledmys Diaz

2017 has been a worst-case scenario for the club’s latest shortstop

Pittsburgh Pirates v St Louis Cardinals Photo by Dilip Vishwanat/Getty Images

It’s the All-Star break, and it’s unclear what will happen at the deadline. The Cardinals remain stuck inbetween, where they could buy or sell at the deadline, depending on how the rest of the month plays out. The Cubs continue to under-perform, the Brewers have done well enough for long enough that we have to take them seriously at this point. The Diamondbacks sit in the first Wild Card and are 9 1/2 games back of the Cubs right now, who are incidentally tied with the Cards. The Rockies have struggled a bit of late, but they were so impressive beforehand that they still sit 7 1/2 games up on the Cards and the Cubs.

To be honest, I still find the Cardinals and Cubs to be better teams than the Brewers, Rockies, and Diamondbacks. Those teams are better than most thought they would be, but one half of a baseball season can only mean so much. Despite the fact that the projections agree that the Cards as better than the Rockies and Diamondbacks, they also see the latter two’s banked wins and the fact that there’s less than half a season left to play. The Cardinals project to catch the Brewers, but they see the Cubs doing better. They don’t, however, project to catch the Rockies and Diamondbacks. According to the projections, In the mean outcome, the Cardinals miss the playoffs.

There’s a probabilistic nature to these things though. The projections give the Cards a 21.8% chance to win the division and a 10.4% chance of winning a Wild Card. Those along with their projected chances in a potential Wild Card game combine to give the Cards a 27.1% of getting to the NLDS. Is that close enough to go for it? Maybe, but it’s definitely not enough to feel all that confident about it.

The season hasn’t gone smoothly so far. Many players have had rough stretches. Aledmys Diaz is one such player, and was recently demoted to Triple-A to figure things out. Diaz himself would say that 2017 has been a disappointment so far. In fact, that’s basically what he said when he was demoted. No one wants to talk openly to the baseball world about their struggles, but I think he showed a lot of character in the way he handled it.

Relativity is a good thing to remember when a player is struggling. In Diaz’s case, he’s fallen out of the highest level of baseball competition, probably only temporarily. He’s still higher on the totem pole than over 99.9% of those who would prefer to play baseball for a living. When we say a player is “bad”, we just mean bad relative to the rest of the very small of pool of the very best ball players our globe can offer.

There’s also the fact that there is nothing to regret even if Diaz never makes it back to the majors. He signed an $8M guaranteed deal, giving him and his family wealth greater than most of us could ever imagine. It’s worked out great for the Cards as well, as so far he’s produced $23.7M worth of value as a Cardinal according to Fangraphs’ value tab.

That said, the goal of today is to find out what’s been going wrong with Diaz in 2017. Before the season, I suggested he join the Fly Ball revolution, as he had a strong overall Exit Velocity but those hard hit balls were in the air less than average.

I also expressed concern about his contact quality back in May. That article was the first time I wrote about‘s six qualities of contact, six different types of batted balls, as grouped by Statcast-recorded Exit Velocity (the speed at which the ball leaves the bat) and Launch Angle (the vertical angle the ball leaves the bat). To best visualize these concepts, Baseball Savant uses a Radial Chart:

I talk about each of these at length in the article linked above, but at the time I made one big mistake: I mistakenly used an incorrect figure for the average wOBA for weak contact, which is defined as any ball under 60 MPH. I’ve been showing a league average wOBA for weak contact as .460, above league average batted ball. I hypothesized that this was because defenses weren’t usually positioned to make an out on a ball that slow.

However, the number Tom Tango reports that the average wOBA for weak contact is actually .046, making it the worse performing batted ball. This doesn’t really change any of my analysis, I never drew a conclusion on a player based on his weak contact numbers. It’s a stupid mistake though, and I apologize to VEB for making it.

Anyway, back to the Radial Chart above. The protractor-shaped image above is used to represent any batted ball in terms of Exit Velocity and Launch Angle. Each dot represents one of Diaz’s batted balls in 2017. The six shaded regions are the six qualities of contact.

While I think the Radial Chart is extremely useful for understanding the concept, it lacks context. Here is the league average rates for each contact quality as well as Diaz’s contact quality over his MLB career.

Aledmys Diaz contact quality breakdown

Player Barrels% Solid Contact% Flares and Burners% Topped% Under% Weak%
Player Barrels% Solid Contact% Flares and Burners% Topped% Under% Weak%
Avg wOBA 1.433 .692 .630 .206 .095 .046
Lg Avg 6.7% 5.6% 24.6% 33.0% 24.5% 5.7%
Diaz 2016 3.8% 5.0% 20.0% 32.0% 33.2% 6.0%
April 2nd - May 15th 3.1% 5.4% 22.3% 27.7% 36.2% 5.4%
May16th - present 4.0% 5.2% 23.0% 31.6% 29.3% 6.9%

Diaz hit a below-average amount of barrels in 2016, the best performing batted ball. He has continued that trend in 2017. Baseball Savant has another stat, xwOBA. That replaces the on-contact portion of wOBA with the average production of each of the hitter’s batted balls. Craig Edwards recently found xwOBA to be more predictive of future wOBA than wOBA itself. Diaz does not perform well by this stat. Among 183 players with more than 500 At Bats in 2016, Diaz had the biggest negative difference between his xwOBA (.322) and wOBA (.376).

It gets worse: Diaz has had a rough 2017 at the plate, good for a 79 wRC+, 21% below average. Statcast doesn’t think he should have even been that good. For Diaz, that translated from a .300 wOBA. His xwOBA was much worse though, at .266. That was the 35th biggest negative difference among 159 hitters with 250 AB in 2017. It’s also the 9th lowest xwOBA among that group. Diaz definitely wasn’t unlucky; he was just lucky he lasted as long as he did.

Much of his difference might come from his impressive IFH% (infield-hit%). Among 170 players with at least 700 plate appearances between 2016 and 2017, he has the single highest IFH% (14.2%). He’s an above-average runner by statcast’s new Sprint Speed metric, with 27.9 feet per second, 86th of 367 players on their leaderboard. That’s nice, but it’s not elite enough to justify the best rate at legging out infield singles. xwOBA might sell him a little short, but it’s not far off by any means.

Anyway, that’s my first point: Diaz’s contact quality has been bad, worse than the results. As I mentioned when I wrote on Diaz earlier though, he can be valuable in other ways to make up for it. The problem is, there’s another problem: Diaz has been more aggressive. Here’s a 15-game rolling average of his swing rates, courtesy of

The Red Baron noticed Diaz’s skyrocketing swinging rates early on. Later, his rates dropped back to normal, and I decided to be optimistic and hope that he was getting back to normal. The opposite has happened though, he was back around the same peaks before he got sent down to Triple-A.

This is occurring alongside yet another problem, a declining contact rate:

Diaz started off fine in terms of contact rate, but in his last 60 games, it’s tumbled. Overall, Diaz has dropped his contact rate from 83.9% in 2016 to 79.7% 2017. Of 162 players with 250 plate appearances in both seasons, that’s the 23rd biggest drop. To be clear, for the year Diaz is still above the league average contact rate of 77.5%, but it’s a troubling trend that saps his value nonetheless.

It turns out these two more recent problems are related. Check this out. This is Diaz’s plate discipline stats, broken down by pitch:

Aledmys Diaz plate discipline breakdown

Pitch 2016 O-Swing% 2017 O-Swing% 2016 Z-Swing% 2017 Z-Swing% 2016 O-Contact% 2017 O-Contact% 2016 Z-Contact% 2017 Z-Contact%
Pitch 2016 O-Swing% 2017 O-Swing% 2016 Z-Swing% 2017 Z-Swing% 2016 O-Contact% 2017 O-Contact% 2016 Z-Contact% 2017 Z-Contact%
Fourseam (FA) 19.8 % 29.5 % 64.0 % 66.9 % 91.7 % 72.7 % 93.9 % 92.6 %
Sinker (SI) 25.7 % 38.2 % 64.9 % 60.0 % 68.1 % 61.8 % 92.5 % 94.7 %
Slider (SL) 37.2 % 46.6 % 79.1 % 75.6 % 56.7 % 46.3 % 88.5 % 91.9 %
Changeup (CH) 33.9 % 35.6 % 68.4 % 86.7 % 48.7 % 61.9 % 84.6 % 80.8 %
Curveball (CU) 26.4 % 46.0 % 51.8 % 49.0 % 65.2 % 47.1 % 82.8 % 76.0 %
Cutter (FC) 29.3 % 42.6 % 67.7 % 77.8 % 70.6 % 80.0 % 90.5 % 85.7 %
Splitter (FS) 50.0 % 46.2 % 100.0 % 100.0 % 50.0 % 83.3 % 100.0 % 100.0 %

His in-zone contact rate (Z-Contact%) has remained steady for the most part, pitch to pitch. his O-Swing (percentage of out-of-zone pitches he swings at) has increased on nearly every pitch, in many cases along with a steady Z-Swing% (percentage on in-zone swings). It’s his O-Contact% (contact% on pitches out of the zone) that is increasing. This and his O-Swing% are conspiring to create Diaz’s extra swings and misses.

This trend holds for many pitches, but the increases are largest with four seamers and sinkers. Curveballs also see a huge increase in O-Swing%, but the fastballs combined make up four times as many pitches, so we’ll concentrate on those.

On the one hand, you can say that the increases in O-Swing% were somewhat offset by swings in the zone. But not all swings in the zone are created equal. Covering the entire plate is tough. Players sometimes have to sit on certain pitches and locations to do damage. Diaz displayed that somewhat in 2016, but his focus has spread in 2017. Here’s a heatmap (another feature from of all of his swings in 2016 (left) and 2017 (right):

Both are centered middle-middle but slightly to the inside half to the right-handed hitter. 2017 is less concentrated though, and sees an increase in fastballs off the plate inside and outside. In terms of in-zone swings, he’s swinging more in the high-outside quadrant and low-outside quadrant.

Diaz might be trying to cover too much area. The results are more swings and misses, more swings at pitches that are hard to do damage on. Let’s look at 2016 and 2017 heatmaps side-by-side again, but this time for Swings and Misses:

Last year Diaz had a hole in his swing on low-inside fastballs. He at least limited the damage, with the highest concentrations coming inside the zone. He’s expanding the zone now though, and the extra swings are misses. He’s also missing less outside pitches I guess, but it’s not enough to cancel out.

Diaz is swinging at more pitches out of the zone, and that expansion of the zone is creating more swing and miss in his game. The result is an increased strikeout rate and decreased walk rate. For a bat-first shortstop with some established contact quality concerns, this is not good news.

And it seems like pitchers have noticed. Here’s one more set of heat maps, this time for all fastballs to Diaz in 2016 (left) and 2017 (right):

In 2016, pitchers targeted mostly low and away fastballs to Diaz. That was true in 2017 as well, but the concentration got a bit lower, and was joined by another concentration inside. Pitchers are working Diaz lower, and also targeting the inside half both on and off the plate more often. Even in 2016, pitchers worked Diaz a little bit under the hands, but they’ve taken that to new heights in 2017.

While pitchers also work him outside often too, he’s made more contact outside. Perhaps to even allow himself to make contact on these outside pitchers, he’s leaving himself vulnerable to swings and misses on inside pitches.

His 8.9% BB rate along with a 13% strikeout rate was reason to be optimistic in 2016. These changes in 2017 have halved his walk rate (4.5%) as well as increased his strike outs (14.2%). And that’s combined with worse contact quality.

Perhaps Diaz gets his head back on straight, and gets back to posting high contact rates along with better swing selection. Even if he does though, he’s still has the contact quality concerns. It’s looking more and more likely that 2016 Aledmys Diaz isn’t coming back.

His projected wRC+ going into 2017 was 107. Since then, it’s fallen to 97. That’s a drop of two-thirds of a win over a full season. Diaz is a shortstop, but also a barely passable one at best, one that needs a strong bat to make up for his defensive shortcomings. In just over a full-season worth of innings at shortstop (only a third of the necessary sample size) he’s been 9.3 runs below the average shortstop (8 runs per 150 games). With the position adjustment (+7.5 runs for shortstops over 150 games), that’s made him about a scratch defender overall. The small sample size gives us a lot of uncertainty in where exactly he lands, but for me personally it’s hard to find someone willing to defend Diaz’s defensive chops.

Things weren’t looking good for Diaz when he was demoted, and they still don’t. In 36 plate appearances, he hasn’t worked a single walk. He’s also striking out 22.2% of the time, the highest rate he’s posted at any stop in the minors or majors. With an extremely low BABIP (.185), he’s posted a 14 wRC+, which translates to 86% worse than the average Triple-A player. It’s only 36 PA, but it’s been a horrific 36.

Hopefully, this is what rock-bottom looks like for Diaz. Perhaps he’s working on his swing and approach, and this is what experimenting with these things looks like. Maybe that’s why they sent him to Triple-A, so a complete re-working could be done outside of major league situations.

However, things look pretty bad right now. Not Allen Craig in 2014 bad, but bad nonetheless. The alternatives at short are also bleak. Okay, Paul DeJong has a 138 wRC+ for the year right now, which is amazing. But he’s doing it in inconceivably unsustainable ways. We’re talking 2015 Randal Grichuk unsustainable. Like Diaz, DeJong is a bat-first player who is only going to work out if he can hit really well, and players that combine walk (3.1%) and strike out rates (29.5%) as bad as his rarely succeed for extended periods of time in the majors. It’ll be fun while it lasts, but long-term, DeJong still has unfavorable odds of becoming an average or better regular. It’s even more unfavorable that if he works out, it’s as a shortstop.

The hope was that Diaz could be a lite version of Hanley Ramerez 2007 to 2014: a guy that consistently had poor ratings at short, but mashed his way to be being a valuable player anyway. But the underlying numbers show that this was always unlikely.

It’s one thing to hope for Diaz to bounce-back. His trade value is almost certainly very low anyway. It’s another thing for the plan at shortstop to depend on that bounce-back. Especially when it’s a completely valid opinion to say that he’s playing out of position at short. He could be a average-ish hitter again, but even if he does, he probably profiles best at third or second anyway.

The Cardinals could use an actual shortstop, one that doesn’t have to be an above-average hitter to make up for his deficiencies of essentially playing out of position. They technically have one true shortstop in Alex Meija, but in his case, it’s unfair to expect the bat to play. He’s been a well-below average hitter in nearly 1,000 plate appearances combined at Triple-A and Double-A. He projects to hit at Kozma-like levels in the majors. Their best long-term solution in house is probably Delvin Perez, an 18 year old who is currently struggling at the plate in Rookie ball.

In other words, the Cardinals have a problem at short. That’s been a recurring problem since the departures of Edgar Renteria and David Eckstein, but it was one that Jhonny Peralta (2014 and 2015) and Diaz (2016) had brought some stability to in recent years. Whether the Cards are buyers or sellers at the deadline, this looks like something the team would be wise to address.