NEW YORK – Before the start of spring training, Toronto Blue Jays third base coach Luis Rivera spent hours studying video of Aledmys Diaz playing the field. Over the course of two seasons with the St. Louis Cardinals, advanced defensive metrics rated the 27-year-old poorly among big-league shortstops and with uncertainty about Troy Tulowitzki’s status, that was a concern.

So Rivera, a former shortstop who works with the club’s infielders, went to work.

“Right away I saw what I needed to do with him,” he says. “I let him work like a week or so and then after that I mentioned to him what I had seen. Everything starts in spring training because it’s hard to make adjustments during the season. You want the guy to feel comfortable on the field. He was willing to do it every day in batting practice.”

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The early returns suggest a payoff for both Diaz and the Blue Jays, which has been crucial after Tulowitzki underwent surgery to remove bone spurs from both his heels.

Over the course of 18 games played so far, a small sample size to be sure, he’s made just one throwing error and, at least to the eye, played a respectable shortstop. More objective measures, which even with a more abundant pool of data to work from don’t tell the full story because not every defensive chance is created equal, also suggest improvement. His defensive runs above average rating sits at 0.4 compared to 2016, when it was minus-4.3 (last year in 589 innings it was 2.6, but his defensive runs saved, or DRS, sat at minus-10).

This season his DRS is plus-1, 12th in the majors, per Fangraphs. Defensively, he’s certainly been better than initial expectations at the time he was acquired from the Cardinals back in December, while at the plate he’s posted a weighted runs created plus of 87, which is below the league average of 100. But with four homers and two doubles in 65 plate appearances, there’s been impact to his contributions.

“At this point, I feel like I deserve and I belong in the big leagues as an everyday shortstop,” Diaz, a native of Santa Clara, Cuba, says through interpreter Josue Peley. “You know how always players say to slow down the game – my first couple of years, coming from the minors to the big-leagues is such a big difference. The adjustments, the game is so much faster. Now, I feel like I’ve slowed the game down. With the pitching staff we have, you get a lot of grounders, we have a lot of guys who throw sinkers. I feel like I’m doing a great job and knowing that I have little bit more experience now and with all I’ve been working on, I feel like I can slow the game down a little bit more.

“It just feels more comfortable now.”

Diaz credits his defensive work with Rivera for that.

While combing over the video, Rivera identified that after Diaz fielded the ball, he would take two, maybe three steps before firing it across the diamond. That’s problematic because not only did the needless strides give runners more time to try and reach the bag, they also altered his momentum, which sometimes led to erratic throws.

Of the 22 errors he’s made over the course of 1,499 big-league innings, 13 of them were with his arm.

Trying to unlearn years of footwork is no simple task, but Diaz committed to it, with Rivera mimicking game speed for him every day he took groundballs. The goal was to make his throw with no more than one step after transferring the ball, allowing his legs to carry him toward the target and keep his arm in line along with it.

“Every time I step on the field and I’m taking grounders I treat it as a game, so when I get into the game, I don’t have to think about anything that I just did in practice. I get into habits and it’s been working pretty well so far,” says Diaz.

“It’s helped me more with my legs. I got more power to throw to first base and I’m more accurate going to the base with my legs.”

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To ultimately stick as an everyday shortstop, however, Diaz will need to be more like the offensive player he was in 2016, when he posted a wRC+ of 133, than last season, when his wRC+ was 78 and he spent time in the minors.

General manager Ross Atkins has repeatedly said the Blue Jays want him to be somewhere in between those two seasons, and if he’s a better than league average hitter, that will compensate for his below average defence.

Diaz feels he’s getting there, too.

“It’s a matter of experience and of learning,” he says. “I’ve been trying to be a smarter hitter. I’ve been trying a little bit to use the whole field and that’s something that I’m still working on it. I’m really grateful to Kendrys (Morales), he’s been helping me a lot to get used to the American League, it’s a little bit different from where I was.

“I have to keep making sure that I put my work in the cage during BP to make sure that I become a better hitter than I was last year, and the smarter hitter I was in the year before.”

Production there will be more important for him now that prospect and countryman Lourdes Gurriel Jr., is on the roster as the backup infielder in place of Gift Ngoepe. Defensively, the 24-year-old remains a bit raw but he’s impressed the Blue Jays with his bat speed.

With a Tulowitzki return not yet in sight, Gurriel is the only alternative the Blue Jays have to Diaz at the moment should they feel a change was needed.

Defensively, at least, Diaz has given them no reason to want that.

“I can tell you that from Day 1 when we got him in spring training to now, he’s improved a lot,” says Rivera. “Hopefully he continues to work on what we’re trying to do with him and he progresses even more.”