According to Baseball America, “Vargas starts his arsenal with a low-90s fastball that features hard sink… He coupled the fastball with a changeup in the low-80s that projects as plus as well as a developing curveball in the upper-70s”.
In the same article Josh Norris interviews 2017 Charleston manager Pat Osborn, who says, “He’s got some sink on his fastball,” Osborn said. “And that changeup, I can’t see it from (the catcher’s viewpoint), but from the side it looks like it’s got some bottom to it, which right around the plate area when the ball meets the barrel, it’s got some bottom and they’re pounding it into the ground.”
Norris writes, “he also showed impressive ability to work ahead in the count, induce weak contact and keep his pitch count low.”
2017 RiverDogs pitching coach Justin Pope was also interviewed by Norris and said, “He’s throwing strikes with his fastball and changeup, which are really good pitches,” Charleston pitching coach Justin Pope said. “His fastball has really good sink. He throws the fastball and changeup for strikes, and he’s developing his curveball, but today he had one three-ball count. He was getting ahead of hitters, and when you get ahead of hitters, it makes pitching easier. Not easy, but easier.”