The owner of an electric arm and immense potential, Espinoza was shipped from Boston to San Diego on July 14 in a trade for All-Star lefty Drew Pomeranz.

The promising young righty has had a strong first run through full-season Class A ball, despite being tasked with facing competition generally three-to-five years his senior, showcasing a lively mid-90s fastball that can flirt with triple digits, a 12-to-6 bender that will flash plus or better, and an impressive changeup with sharp fade and dive that can likewise come with at least plus grades from evaluators when on.

As would be expected of an 18-year-old in Class A ball, there are still rough edges for Espinoza to smooth out. While the arsenal is big-boy quality, Espinoza is still learning to wield it with consistency, and can often times struggle with effective execution in the zone – particularly with his curveball. Over his last seven starts (covering each of his appearances in June and July), Espinoza has averaged upwards of 20 pitches per inning, often times running deep into counts and allowing hitters to sit on fastballs. While he is generally around the zone, he will also slip into bouts where he drives his fastballs up, and particularly to the arm side, though he has generally done a good job of quickly correcting course in-game.

While his slight stature and impressive raw stuff has drawn him unfair comparisons to Red Sox great Pedro Martinez, there is indeed true frontline upside in Espinoza, with a chance for three legitimate double-plus offerings, and with an ability to dominate opposing lineups when it all comes together. That staggering version of Espinoza, however, is still some time away. And while his natural talents, easy delivery, and high-quality arsenal could all congeal in very short order, there are likely to be some bumps in the road along the way. If the undersized righty is able to shoulder the trying load of a big league starter, he has the potential to be one of the best in the game.