Gavin Stone
I’ll keep this brief. I wasn’t a fan of Stone entering this year, which is weird because his minor-league stats look pretty good on a second look now. But after his first two major-league starts, maybe my instincts were correct after all. Those two starts showed Stone’s repertoire to be very shallow, making it challenging to execute without pinpoint precision. Given a 7 walk to 2 strikeout ratio as of writing this, it’s fair to say that hasn’t come around yet.
Stone relies almost entirely on his changeup, having thrown it 43% of the time in his debut against the Phillies and 34% of the time against the Braves. He also throws a fastball (50%) and a slider (12%), both of which look OK but are nothing special yet. His changeup (15% CSW) and fastball (23% CSW) fooled no one against the Phillies, but all of his pitches performed far better against the Braves, with a 40% whiff rate on the fastball and changeup on 15 swings each, leading the way. I still question its sustainability, though.
Gavin Stone was all over the place and struggled to elevate the fastball in his debut. He needs to keep those fastballs up and the changeups down to find success.
To succeed, he needs the changeup to reach its potential and have a second offering that he can also turn to. His fastball looks decent with above-average ride, and his slider creates whiffs at a decent rate, but one has to become a genuinely reliable pitch. Right now, he resembles a pitcher like 2022 Giolito: a pitcher with an above-average changeup that gets knocked around because none of his other pitches help him at all. Even in that Braves matchup where he fared slightly better, he walked 5 and only struck out 1. Hopefully, he keeps getting chances with Julio Urias and Dustin May hurt, but right now, he seems like a 4 ERA guy if all goes to plan. There’s just not enough there for me. Given that the Dodgers already sent him down before, they seem to concur.
Brandon Pfaadt
I’ve always believed in Pfaadt’s pedigree much more than Stone, so his results are far more disappointing. Pfaadt has had four starts thus far in his career, and aside from a decent outing against the Giants, where he managed hard contact well with good fastball elevation, he has struggled to get any footing.
Against RHB, he goes Fastball/Slider, and against LHB, Fastball/Changeup/Slider with some Curves mixed in as well. My diagnosis of Pfaadt’s issues is similar to Josiah Gray’s - his two primary offerings vs. LHP - the fastball and changeup - are getting him into trouble. But my proposed remedy is different - the changeup actually creates plenty of swing and miss vs. LHB - a 15% swinging strike rate and a decent 12.8% CS rate on a pitch thrown out of the zone nearly 80% of the time (9th percentile). He’s clearly struggling with command on the pitch, with just a 21.6% chase rate (33rd percentile) as a result, and I believe with more robust control, it can return solid results—no need to scrap it, unlike Josiah.
His fastball has a solid approach angle (+.32॰ VAA) and decent movement, but nothing extraordinary. 93.5 mph doesn’t inspire much confidence either in tandem. It’s suffered from weak command thus far, but I don’t see much here, even with great fastball/slider separation in the north and south of the zone. His slider is good enough to carry the load in the partnership, but I’d like to see much more from it, either in whiffs or control. His fastball usage is the 17th highest of all starters too?? Not ideal.
His slider has performed very well as his primary secondary overall with an 18.3% swinging strike rate and has been a nightmare for righties: 24% swinging strike rate at 35% usage. There’s a lot to like and a lot to build on: as said before, the fastball relies on its continued success. Undoubtedly, he has to turn to it more to build some solid outings.
Lastly, his curveball. He throws it 9% of the time vs. LHB for a decent 27% CSW rate and doesn’t get knocked around like the fastball or changeup. I’m not sure it’ll see any increase in use in the medium term, but if it does, I’d guess it’d be vs. RHB with how the fastball is getting knocked around. It’s worth the experiment at this point.
Despite how his changeup appears to be performing based on PLV (average expected pitch result based on pitch quality from 1-10), I think it has the potential to be an effective out-getter vs. lefties.
My conclusion on Pfaadt can be taken two ways. One could see his effective slider and promising changeup and curveball as a sign of things getting better sooner rather than later, or the weak command of his changeup and mediocre fastball dooming him to a 2022 Josiah Gray type campaign, where lefties feast on his poor changeups (24.2% groundball rate overall? That just isn’t right.). I lean more towards the former because he doesn’t have to change his pitches; it’s all about refining his in-game performance and pitch selection. Gray had to add a brand-new cutter in the offseason to replace his horrible changeup if you recall.
Suppose he can go slider-heavy vs. right-handed hitters, refine the changeup vs. left-handed hitters, and mix in his fastball and curveball effectively in between. In that case, I can see an above-average season (3.70 ERA?) the rest of the way. Otherwise, Dbacks fans might have to wait until 2024 for the performance promised by his prospect pedigree.