Cal Quantrill’s potential is considerable. Drafted eighth overall by the Padres in 2016 despite having undergone Tommy John surgery while at Stanford — he missed all of his junior year and much of his sophomore season — the 23-year-old right-hander possesses a combination of plus stuff and pitchability. Baseball America and MLB.com rank him as the fourth-best prospect in the San Diego system, while our own list — expect that soon — will have him a bit lower.

Quantrill, who is lauded as having one of the best changeups in the minors, has made seven starts for Double-A San Antonio this season and has a 3.52 ERA, a 3.29 FIP, and is striking out 8.2 batters per nine innings. He discussed his multi-pitch mix, and his take-no-prisoners approach, during spring training.

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Cal Quantrill: “I’m a fastball pitcher. Am I a power pitcher? I guess that would depend on how you want to define it. To me, a power pitcher is someone who attacks hitters, regardless of how fast their fastball is. They don’t fool around — they don’t play around with the edges of the strike zone — they go right after them. Getting ahead in the count is something I take great pride in. I try to make hitters get themselves out, and I want that to happen quickly so that I can go deep into games.

“I throw both [two-seamers and four-seamers], probably more four-seamers. When I’m throwing my fastball the best, it’s got good carry — it’s got good life — and I’m locating. It’s all pretty basic stuff. To me, it’s about throwing with conviction and executing my pitches.

“I use both twos and fours down. I’m not exclusively one or the other. I’m also not afraid to go up in the zone. You can execute fastballs in all four quadrants, regardless of what that fastball is. I use all four as opposed to focusing more up-down or in-out. Again, it’s pretty basic stuff. If you execute pitches more often than you don’t, you’re going be a pretty successful pitcher regardless of what advanced analytics say.

“My spin rate? I know some of the numbers, but I don’t think that’s something you can drastically change. It is something you look into. You see who you are, and you see what you can do with it. That being said, it’s just another tool in the box to analyze and to potentially help you.

“I’m told all the time that my changeup is my best pitch, but if I didn’t have a good fastball, I don’t think any of you guys would say anything about my changeup. All pitches come off the fastball. That said, I didn’t throw a breaking ball early on [growing up], so the changeup is something I’ve worked on for a long time.

“It’s a feel pitch. You throw it as hard as you can and let it come off your fingertips a little differently. It’s something I’ve played around with for years and years now, and I feel very confident in it. It’s a pitch I go to in important counts, which I think is a separator between me and other guys who throw a changeup.

“It’s mostly a four-seam changeup, although I actually throw it with thee or four different grips. Different grips get different movement. I try to change planes with my changeup. I want it to appear as if I’m throwing a fastball, and have it not come out where they expect it to be. Depending on the hitter, and how we’ve decided he’s swinging the bat that day, we’re going to go a different type of changeup. I’ll throw it a little harder, throw it a little softer, see if I can get it to fade more, or drop more.

“They’re not drastically different, but they are slightly different grips… It’s not something I want to explain in detail, but I’m holding it different. I’m feeling it off different fingers more, or less. It’s something I’ve gotten to from lots of years of throwing it different ways, and seeing which ones work. The changeup is a great pitch. In my opinion, as long as you have a fastball, you should have a changeup.

“My breaking pitch right now is a slider. Last year I threw a curveball and a slider. It’s about what is going to be the best at the highest level, and I think we’ve come to the agreement that it will be the slider. That’s something I’m focusing on this spring. Let’s see if we can make that pitch as good as we can before we think about expanding the repertoire.”

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Author’s note: Padres director of player development Sam Geaney confirmed this week that Quantrill is not currently throwing a curveball, but only fastballs, changeups, and sliders.