It’s time people start paying attention to Engelb Vielma. Vielma, who turned 21 a month ago, has been the starting shortstop for the Miracle this season. Always known as a top flight defensive prospect, the diminutive Vielma has done little to discourage that perception in his first 2 seasons of professional ball: in the Midwest League in 2014, Vielma posted a .636 OPS (a wRC+ of 84) and so far in 2015 his OPS sits at .648 (wRC+ of 99). Certainly, this represents a modest improvement, but it is nothing to get excited about. However, taking a closer look at Vielma’s monthly splits, it becomes clear that he has made some significant in-season improvements as a hitter.

The first thing that sticks out is how dreadful Vielma was in April and May—combined his OPS was .463—and how solid he has been since, posting an OPS of over .770 for 3 straight months. But overall, looking at 5 straight months of data like this has some flaws: for one, the sample sizes are relatively small; and two, it’s a little more difficult to pick up on trends patterns. My solution to this is to create 3, 3-month splits (April-June, May-July, June-August), similar to rolling periods used in the financial industry. Let’s take a look:

As you can see here, Vielma has made some pretty tremendous strides. This is especially true when looking at his plate discipline: his BB% has increased over each of these splits and his K% has fallen, leading to a consistent improvement in his BB/K ratio. Furthermore, while Vielma only improved modestly in these 3 categories from the 1st split to the 2nd split, he has seen a dramatic improvement from the 2nd split to the 3rd split. And while Vielma’s isolated power has improved less consistently, his OPS has also improved by leaps and bounds.

Overall, Vielma’s numbers have improved—albeit rather modestly—from a year ago. Once again, he is walking more (6.1% to 6.3%) and striking out less (15.5% to 14.6%), which has certainly contributed to the modest increase in OPS (.636 to .649). And while this increase is small (and his power has decreased), it has been done in the context of a much difficult environment for hitters.

Clearly, Vielma has made terrific in-season improvements as a hitter. Combined with his modest overall improvement from a year ago, this suggests that he should be ready to begin 2016 in AA, despite rather mediocre season-long number.

Another important development for Vielma has been his basestealing. As a player who has very limited power—and has shown no signs of developing any more—being able to create extra runs on the basepaths will be necessary for Vielma to establish himself as a valuable offensive player. While I don’t have any statistics regarding Vielma’s ability to take an extra base after a hit, he has shown dramatic improvements as a basestealer this year. In 2014, Vielma stole 10 bases on 16 attempts in 112 games. So far in 103 games this year, he has stolen 29 bases in 39 attempts. Not only has he stolen nearly 3 times as many bases as last season, Vielma has also greatly improved his success rate from a dreadful 62.5% (well below the 2014 Midwest League average of 68%) to a respectable 74% (well above the 2015 Florida State League average of 67%).

With Nick Gordon on his heels and Jorge Polanco ahead of him (not to mention Brian Dozier), Engelb Vielma will have a hard time becoming a starter for the Twins. But as a player who is stellar defensively, emerging as a basestealer, and improving as a hitter, he has firmly established himself as a legitimate prospect worth watching.