READING — Righthander Ramon Rosso dominated in both low and high single-A last season, and now the Phillies prospect is doing the same for double-A Reading.

While some pitchers throw harder, Rosso has shown an ability to locate his pitches, led by a devastating cutter and a slider.

“He throws that hard cutter, and it’s a hard pitch to hit,” Reading outfielder Adam Haseley said.

Since being released by the Los Angeles Dodgers in July 2016, Rosso, who turns 23 on June 9, aced every test at each level in the Phillies’ minor league organization.

A Dominican Republic native, Rosso signed for a $62,000 signing bonus with the Dodgers in July of 2015, but he never pitched an inning for their minor-league affiliates.

He was signed as a free agent by the Phillies on June 2, 2017, and made his debut in the Dominican Summer League three days later.

Rosso also pitched for the Gulf Coast League Phillies and short-season Williamsport that summer. Last year at low single-A Lakewood, he was 5-1 with a 1.33 ERA, then finished the season at high single-A Clearwater, where he went 6-2 with a 2.91 ERA.

This season in seven starts with Reading, he is 3-1 with a 2.52 ERA. In 35 ⅔ innings, the 6-foot-4, 230-pound Rosso has 38 strikeouts and 10 walks.

“He mixes a change-up with his cutter and slider, and that is really tough,” manager Shawn Williams said. “He has a pretty high ceiling.”

Rosso earned the win in Saturday’s 4-1 victory over the Portland Sea Dogs. He allowed one run on four hits over six innings, striking out three and walking none.

What made the performance more impressive is that it came after his only hiccup of the season. During his previous start, Rosso allowed six earned runs in 3 1/3 innings during a 15-2 loss against Akron.

“I forgot about that last start and had my mind on this start,” Rosso said after Saturday’s win.

It was the second time this season he has pitched six innings. Rosso threw 81 pitches, 52 for strikes.

“That is probably the most important thing, to bounce back like that, the way he gave us a great start,” Williams said. “You are not going to be great every night, but when you bounce back like that, it is pretty impressive.”

On Saturday, Rosso consistently threw in the low 90s, topping out at 94 mph. Where he has enjoyed great success is from the movement of both his cutter and slider.

“Both are exactly the same pitches except one is 91-92 and can get to 94, and the slider is 80-82, and it comes at them exactly the same, so I can’t imagine that being fun to hit,” Williams said.

Rosso says one reason he is pitching well is that the Phillies have made him feel comfortable and, in turn, confident.

“The Phillies have helped me a lot, and I have been throwing the ball pretty well,” he said.

Rosso said he thinks his aggressive mindset is one reason for his recent success.

“When I go to the mound, I want to attack hitters early,” he said.

Rosso, who is The Inquirer’s No. 17th-ranked Phillies prospect, still has plenty to do to refine his craft.

“Just for him, it is probably his command that has to improve,” Williams said. “He has good control but there is a difference between control and command, and, when he starts throwing the cutter exactly where he wants to, it will be pretty hard to hit.”