Scouting grades: Fastball: 60 | Curveball: 55 | Changeup: 45 | Control: 45 | Overall: 45
The Blue Jays landed Diaz at the outset of the 2014-15 international period, signing him for $1.6 million one day after they had inked phenom Vladimir Guerrero Jr. The Dominican right-hander flashed promise early in his career but also produced uneven results as he struggled to throw strikes. While he still has gains to make with regards to his control, Diaz's stuff has steadily ticked up each year as he's added strength and logged experience. It all started to click for him in 2018, as Diaz pitched his way up to the Florida State League as part of a breakout campaign.
Diaz's athleticism and quick arm help him generate easy velocity. He sits in the mid-90s with a lively fastball that he pairs with an above-average breaking ball. He misses bats with both pitches, while the crossfire in Diaz's delivery gives him natural deception and makes him especially tough on right-handed hitters. His changeup remains a work in progress, though Diaz has made strides in developing in the past year to the point where it's at least usable against left-handed hitters. His control, though still below-average, was markedly better last season as he trimmed his walk rate to 3.2 BB/9 from 4.8 in 2017.
After wearing down physically early in his career, Diaz has worked hard to add strength and improve his durability. His efforts showed in 2018 in the form of 147 1/3 innings, nearly double his workload from the previous year. Diaz's all-around progress continues to give him life as a starter, though many scouts believe he's ticketed for the bullpen, where his fastball-curveball combo could play up in short bursts. Diaz could very well debut in that role in 2019 after the Blue Jays added him to their 40-man roster during the offseason.
Statcast - Pitching
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Toronto Blue Jays recalled RHP Yennsy Diaz from New Hampshire Fisher Cats.
Toronto Blue Jays optioned RHP Yennsy Diaz to New Hampshire Fisher Cats.
Toronto Blue Jays recalled Yennsy Diaz from New Hampshire Fisher Cats.
RHP Yennsy Diaz assigned to New Hampshire Fisher Cats from Buffalo Bisons.
Toronto Blue Jays optioned RHP Yennsy Diaz to Buffalo Bisons.
Toronto Blue Jays selected the contract of Yennsy Diaz from Dunedin Blue Jays.
RHP Yennsy Diaz assigned to Dunedin Blue Jays from Lansing Lugnuts.
RHP Yennsy Diaz assigned to Lansing Lugnuts from Bluefield Blue Jays.
RHP Yennsy Diaz assigned to Bluefield Blue Jays from GCL Blue Jays.
RHP Yennsy Diaz assigned to GCL Blue Jays from DSL Blue Jays.
RHP Yennsy Diaz assigned to DSL Blue Jays.
Toronto Blue Jays signed free agent RHP Yennsy Diaz to a minor league contract.