Wish I could see any evidence, in his record at any level, that Quantrill has a future as anything but a back-of-rotation mediocrity.
This may not answer the question for you, but here’s what I find encouraging about Quantrill.
Here’s a list of the 2019 starting pitchers ranked by lowest average exit velocity against:
Yarbrough (84.0 mph), Hendricks, Ryu,
Martin Perez, Maeda, Woodruff,
E. Rodriguez, deGrom, Houser, Clevinger, Flaherty, Wheeler, Syndergaard, Gio Gonzalez, Vargas, Castillo, Minor, Sabathia, Anibal Sanchez, Berrios, Chase Anderson, Eflin, Morton, Alcantara, Milone, Shaun Anderson, Greinke, Paddack, Ray,
Quantrill (86.9 mph).
Lotta excellent pitchers in this group. Limiting hard contact is a skill, and Quantrill was 30th among 144 qualified starting pitchers.
Now if we reorder that same group by average fastball velocity (2019):
Syndergaard, deGrom, Wheeler, Castillo, Woodruff, Alcantara, Clevinger,
Quantrill, Morton, Houser, Perez, Paddack, Flaherty, Eflin, C. Anderson, Rodriguez, Berrios, S. Anderson, Minor, Ray, Maeda, Ryu, Sanchez, Greinke, Gonzalez, Sabathia, Yarbrough, Milone, Hendricks, Vargas
And if we remove the parameters of the original list and just list hardest fastballs in MLB in 2019 (min. 100 IP), here are the only pitchers from the original soft-contact group who appear in that top 30:
Syndergaard, deGrom, Wheeler, Castillo, Woodruff, Alcantara, Clevinger,
Quantrill, Morton, Houser, Perez
It’s maybe kind of arbitrary to link a ability to throw hard with an ability to limit hard contact, but the pitchers who do both are very few, and good, and Quantrill appears to be one of them.