St. Louis Cardinals: Expectations for Aledmys Diaz in 2017

Jeff Curry-USA TODAY Sports

In 2016, Aledmys Diaz went from a player left off the opening day roster to the St. Louis Cardinals shortstop of the future. What does 2017 have in store for the young star?

Prior to the 2016 season, St. Louis Cardinals All-Star shortstop Aledmys Diaz had very little minor league experience, let alone minor league success. In 2014, he hit only .273/.324/.441 over 47 games in Springfield and Palm Beach. In 2015, he began the season in Springfield. He would hit only .230 through June before being designated for assignment on July 8th of 2015.

This roster move sparked Aledmys Diaz. He would add a small leg kick to his swing to help with his timing at the plate. Then he went on a tear. After rebounding slightly in July, Diaz would mash to a .373/.432/.701 line over eighteen AA games in August before being called up to Memphis. He would continue his hot streak with the AAA team, hitting .380/.448/.620 before posting another stellar .315/.370/.616 line over twenty games in the Arizona Fall League.

Yet, heading into the 2016 season, the St. Louis Cardinals were planning on using Jhonny Peralta as the everyday starter at shortstop. He would be spelled by offseason acquisition Jedd Gyorko and Greg Garcia.

Aledmyz Diaz would start the 2016 season in AAA, where he had only played a total of fourteen games, all in 2015. This was not surprising given that Diaz had only recently hit his stride in the minor leagues and still had to adjust to playing shortstop at the professional level. Additionally, he needed to prove he had actually improved at the plate and wasn’t simply benefiting from a small-sample size hot streak.

Then on March 10th, Jhonny Peralta underwent surgery to repair a torn ligament in his left thumb. Just over a week later, the St. Louis Cardinals signed Ruben Tejada to compete with Jedd Gyorko for the starting shortstop position until Peralta returned.

However, in the club’s final Spring Training game, Ruben Tejada suffered a strained hamstring and was placed on the 15-day DL a few days later. The plan then was for Gyorko to serve as the starting shortstop, at least for the time being.

One more injury occurred on opening day, as Tommy Pham suffered a strained left oblique. When Pham was placed on the 15-day DL, the corresponding roster move was to call Aledmys Diaz up to the Major Leagues before his season in Memphis even started.

It’s hard to believe the string of injuries which had to occur before Diaz would get his opportunity for the St. Louis Cardinals. But on April 5th in the team’s second game, Aledmys Diaz would get his chance, and he would make himself a fixture for the present and future of the St. Louis Cardinals.

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Aledmys Diaz breaks out in 2016

Following a Spring Training in which he only hit for a .265 average and had only a .972 fielding percentage (FDP), the St. Louis Cardinals and fans were unsure how Aledmys Diaz would contribute to the Major League club in 2016. However, injuries forced the Cardinals hand, and Diaz made his debut in the team’s second game on April 5th.

The experiment unfolded better than anyone could have imagined. Aledmys Diaz would hit safely in his first five games on his way to a .423/.453/.732 line in April. He was arguably the best hitter in the entire MLB over this stretch, as his 1.186 OPS led the league at the close of the first month.

This opening act cemented Diaz’s place in the St. Louis Cardinals lineup for the rest of the 2016 season. Unfortunately, his stellar rookie season would be interrupted when he fractured his right thumb on July 31. He would miss over a month with this injury, before returning on September 12th until the season’s end.

Ultimately, Diaz accumulated 2.7 fWAR, good enough for third among St. Louis Cardinals position players and fifth overall on the team in 2016. He would join Matt Carpenter on the 2016 National League All Star team. His final batting line of .300/.369/.510 earned him fifth in NL rookie of the year voting.

Diaz achieved remarkable success in his first season. In the span of a year, he went from being dropped from the forty man roster and being unclaimed off waivers to being a fixture at one of the most positions in baseball for a perennial contender.

Grade: A+. Given his limited professional experience and unexpected timing of his call-up, Diaz flourished in his rookie season with St. Louis. His hot start ensured he remained in the lineup, and he was one of the most important pieces of the 2016 season.

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How can we expect Diaz to improve defensively in 2017?

Aledmys Diaz admittedly struggled to man the shortstop position at the start of his first MLB season. However, he did show some improvement over the year, and this is the area the St. Louis Cardinals are expecting the most improvement going forward.

Overall, Diaz posted a -8.4 UZR and -11.4 UZR/150 at shortstop defensively in 2016. Among the 28 shortstops with 750 or more innings at short last season, he ranked 22nd and 23rd in these ratings, respectively. His overall FDP of .961 ranked 26th. In short, he was bad.

However, just looking at these numbers doesn’t tell the whole story. While monthly UZR splits are not available, we can look at how Diaz’s defense progressed by dividing his season into three parts. Diaz played shortstop in 106 games in 2016 while missing all of August and part of September due to injury.

The first section covers Diaz’s first 31 games with the St. Louis Cardinals. Over this period, which ran until May 13th, Aledmys Diaz was the owner of a .915 FDP at shortstop. For comparison, the worst FDP among the 28 player sample discussed was .956. In this period, Diaz was atrocious defensively. However, despite his obvious struggles on this side of the ball, his bat kept him in the lineup.

The next period ranges from his 32nd game through his 53rd game. Over this period, Diaz compiled a .960 FDP. While this would still rank near the very bottom of the shortstops sampled over a full season, it was a noticeable improvement from his struggles early in the season.

The final section covers half of Diaz’s campaign, from his 54th game until the end of the year. Over this period, Diaz held a .986 FDP. Over a full season, this would rank top five among the sample shortstops.

Of course, FDP tells only a very small and somewhat skewed version of the defensive story. However, it is an important part of Aledmys Diaz defensive rating with the St. Louis Cardinals in 2016. An infielder’s UZR rating is the sum of his double play runs above average (DPR), range runs above average (RngR), and error runs above average (ErrR). The UZR/150 is this sum scaled to 150 games played.

An improvement in Aledmys Diaz’s FDP would mostly impact his ErrR. Over his 910 innings at shortstop in 2016, Diaz accumulated a negative 3.1 ErrR (or about -4.5 per 150 games) on his .961 FDP.

However, if we acknowledge the improvements he made during the season and set our 2017 expectations at the .986 FDP, we can project what his improvement in ErrR, and subsequently UZR and UZR/150, will look like.

There were four players who were within .002 of Diaz’s second half .986 FDP for their own full season: J.J. Hardy, Freddy Galvis, Asdrubal Cabrera, and Jordy Mercer. These players combined to average 4.1 ErrR, which equates to approximately a 4.5 ErrR per 150 games.

Therefore, assuming that Diaz only improves his ability to field the balls he can get to with his current range and does not get any better at turning double plays, Diaz would be 7.6 ErrR better. This would be a positive 7.6 improvement to his UZR and a 9.0 improvement to his UZR/150.

We do know, however, that Diaz is working to get better this offseason. He will come into next season more ready for the grind of an everyday MLB shortstop. It is reasonable, and perhaps even likely, that Diaz will improve other aspects of his defensive game before next season.

This past year, Diaz’s RngR was a negative 5.2 and approximately negative 7.5 per 150 games, while his DPR was negative 0.1. If Diaz is able to improve his range by about five runs per 150 games while posting a 0.0 DPR, he would improve significantly at shortstop. This would improve his UZR by about three points and his UZR/150 by five points.

Assuming ten runs per WAR, this would improve Aledmys Diaz’s value to the St. Louis Cardinals by 1.0 WAR in 2017.

Jeff Curry-USA TODAY Sports

How will Aledmys Diaz fare at the plate in 2017?

Aledmys Diaz’s value to the 2016 St. Louis Cardinals came primarily at the plate. Among Cardinals with more than 100 plate appearances, Diaz ranked second with a .300 batting average, third with a .369 on-base percentage, first with a .510 slugging percentage, and second with a wRC+ of 132.

There isn’t much that suggests Diaz will regress at the plate in 2017. With a walk rate of 8.9% and strikeout rate of only 13.0%, Diaz was not overly reliant on his batting average on balls in play (BABIP). In fact, his .312 BABIP would have rested comfortably in the middle-third among qualified hitters in 2016 and is close to his Minor League career .305 BABIP.

One sign which might indicate Diaz takes a step back at the plate for the St. Louis Cardinals in 2017 is his slash line after his hot April. April was the only month in which Diaz hit above .300, and his line from May 1st on was .273/.352/.462. This equated to approximately a 122 wRC+ instead of his season line of 132 wRC+. Of course, that would still be a good bat to have near the top of the order.

More troubling is Diaz’s line drive percentage (LD%) in 2016. Line drives are the most likely to go for hits and support a strong BABIP. Unfortunately, Diaz’s LD% this past season was only 15.6%, which would have ranked last among all qualified MLB hitters. Only two of the eight players with a LD% of 17.0% or lower had a BABIP above .300.

Looking further into Diaz’s batted balls, it is clear that his BABIP was supported by an abnormally high infield-hit percentage (IFH%) of 15.8%. He was one of only three shortstops with a IFH% greater than 10.0%, with second place in this category a whole 4.5% behind him.

It is true that faster players are more likely to get infield hits. However, Diaz’s Speed Score (Spd) of 4.3 ranked only 20th among the thirty-four shortstops with 300+ plate appearances, according to FanGraphs. The twelve other players whose Spd ranked between 4.0 and 4.9 averaged only a 6.7% IFH%. If Diaz regressed to this rate, he would have had 14 less hits over the course of the past season, which in turn would have dropped his slash line to .265/.345/.455. It is unreasonable to expect Diaz to continue to outperform the field with regard to IFH%, so it is likely that he will see his batting average and overall line regress in 2017.

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Prediction: Even with some regression at the plate, Diaz will likely be worth 2.5 to 3.0 WAR as a hitter in 2017 if he remains healthy for the full season. Steamer Projections currently predicts Diaz to accumulate 2.8 WAR on the back of average defense and a .282/.342/.453 line. Diaz’s total value will be dependent on the strides he makes as a defender, and I project him to gain 1+ WAR as a defender in 2017. At the plate, I predict Aledmys Diaz will hit .280/.350/.470 to be worth a total of 4.0 WAR, further cementing himself as one of the St. Louis Cardinals best players.