Del Rosario made his state-side debut in 2016 totaling 51 1/3 innings in 12 rookie ball starts. The righty struck out 53 while allowing just 13 earned runs on 42 hits and nine walks – good for a 5.89 SO/BB rate, 0.994 WHIP and 2.28 ERA. Through two full season starts with Class A Cedar Rapids he hasn’t missed a step, as the former J2 signee has tallied 10 2/3 innings of work and allowed one earned run on five hits and three walks while punching out 14.

In his opening day start at Beloit, Del Rosario sat comfortably in the 89-to-93 mph velocity band with his fastball, bumping 95 mph on multiple occasions and showing solid arm-side life. His best secondary offering was an above-average changeup that came with big-time arm speed and plane deception, proving particularly effective against same-side bats, drawing empty swings and soft contact alike. He spun both a low-80s slider with two-plane action and an upper-70s curveball with solid shape and average depth. The slider looks like the better offering of the two, working well out of though both could be at least average offerings in time.

Del Rosario works with a quick and easy arm action, decelerating well while maintaining good balance and a steady head throughout. He’s more control over command at present, but it’s solid-average control that should grow to plus once he has cleaned up some of the idiosyncrasies in his mechanics – particularly exiting his step-in to and through the start of his stride – that can periodically throw of both his timing and the consistency in his release. It’s an awfully impressive skill set in a precocious package, making Del Rosario a must follow in 2017, and excellent candidate to shoot up prospect lists by season’s end.