By Cole Shelton

Canadian Baseball Network

Aledmys Diaz practically came out of nowhere for the St. Louis Cardinals in 2016.

Diaz was not supposed to make much of an impact that season, but he blossomed into an National League All-Star, and the Cardinals' starting shortstop. However, a year later, Diaz struggled and was back in the minors and was ultimately traded this off-season to the Toronto Blue Jays.

Following the trade, many Blue Jays fans questioned the move due to Diaz's poor showing at the plate in 2017. But when you take a deeper dive down into things and look at what changed, it is quite clear what Diaz was doing wrong in 2017.

Now, in 2018, the Blue Jays are hoping Diaz can be closer to the 2016 version than the 2017 version. Right now, Diaz is expected to play the bulk of the games at shortstop, and having him at his 2016 form may propel Toronto into a few more wins.

2016 Season

In his rookie big league campaign, everything was going right for Diaz. He finished the season with a .300 batting average along with 17 home runs, 65 RBIs, and a .369 on-base percentage for the Cardinals. He was  voted into the All-Star game in his first year in the majors.

But it’s not just those numbers where Diaz impressed at the plate. Diaz was also making solid contact on every pitch that was thrown his way. He registered a .248 average against two-seam fastballs, the lowest batting average of any pitch for Diaz in 2016, according to baseballsavant.mlb.com.

While Diaz was making contact with every pitch thrown his way, he also had a good eye and was laying off pitches outside the zone. In 2016, Diaz struck out just 13% of the time, and walked 8.9%, while swinging at just 27.4% of pitches thrown outside the zone. He made contact 67.5% of the time when he swings at pitches outside the zone, according to Fangraphs.

Also, Diaz was making contact on 91.2% of pitches thrown at him that were in the zone, and an astonishing 83.4% contact on every pitch thrown.

Diaz was making a lot of contact, and laying off bad pitches which are a key to success for any player. With Diaz making a lot of contact and putting the ball into play, many would think some of his contact would result in weak dribblers, and some were, but, according to Fangraphs, he was making a lot of medium and hard contact on the ball. Diaz was making medium contact on 49.4% of all his hits, while his hard contact was 31.5%. Hard contact usually results in doubles, or home runs.

While Diaz was a relative unknown to many entering 2016, he sure made his mark . He made pitchers pay for their mistakes, — when they threw inside the zone — and laid off pitches outside to make the pitcher's job tougher. Ultimately, the Cardinals got a 2.7 WAR (wins above replacement) player who came from the minors.

2017 Season

Entering 2017, Diaz had sky-high expectations after his very good 2016 season. However, Diaz did not live up to those expectations and was sent to the minors during the season. But how could a player go from such a high one year to such a low the next?  The answer is simple, Diaz started doing something bad — which he wasn’t doing in 2016 — he started to swing at more pitches and not take the borderline pitches, which resulted in more strikeouts, more soft contact, and overall bad numbers.

In 2016, his worst pitch thrown at him was the two-seam fastball where he still had a .248 average. In 2017, however, Diaz was worse than that with four-seam fastballs (.229 batting average), and changeups (.235 batting average), per Fangraphs.

In 2016, Diaz was making contact on more than the majority of the pitches thrown at him, and laying off bad ones, he wasn’t doing that in 2017. Rather, he was swinging at more pitches, which saw his strikeout rate jump one percent to 14% — although, it is a lot worse than it looks given he had fewer at-bats in 2017 — and saw his walk rate fall from 8.9% to 4.3%, according to Fangraphs.

He also swung at 52.4% of all pitches thrown his way and made contact on just 83.4% of that, a huge drop in those numbers.

While Diaz was swinging more and walking less, all that swinging resulted in softer contact. In 2016, he made just 19% soft contact but that number jumped to 23.2% in 2017, while his hard contact fell from 31.5% to 23.6%, a drastic drop, which showed in fewer home runs and fewer doubles.

Ultimately, swinging at more pitches and taking less pitches resulted in more strikeouts and softer contact rate which made his 2017 season a lot worse.

How he can improve in 2018

Now, Toronto fans are now wondering how can Diaz get back to his 2016 form. Well, his 2017 season wouldn’t have actually been that bad if he was in the Rogers Centre. According to baseballsavant.mlb.com, Diaz would have had eight more home runs than he did in 2017 if he were playing at the Rogers Centre, compared to Busch Stadium in St. Louis.

Right off the bat, coming to play at the Rogers Centre will help Diaz, but what will also help him is laying off pitches. Diaz swung way too much in 2017 and was swinging at bad pitches. If he can lay off pitches with the Blue Jays, the strikeout rate will go down, while he will also make less soft contact.

Ultimately, all Diaz needs to do is just work on what pitches are in the strike zone and which aren’t as that was his biggest problem in 2017. Nonetheless, it is up to Diaz to work on that and try to be a better hitter in 2018, which his new club and Blue Jays fans will be hoping for.