Inside D-backs Pitching Development with Dylan Olsonawski in the Arizona Fall League
Diamondbacks Arizona Complex League pitching coach Dylan Olsonawski is getting a quality opportunity in the Arizona Fall League. In addition to coaching up five pitchers in his own organization, he's working with pitchers from four other organizations.
"You get perspectives from outside the org. I've only been with the D-backs on the pro side, so it's definitely nice. You get coordinators, directors coming into town. You get different perspectives on how to approach working with guys. It's just nice having different guys around."
He's spent most of his time working with Rockies' Coordinator of Pitching Strategies Flint Wallace. Wallace carries more than two decades of experience in pitching development, in both college (Weatherford) and in personal training facilities. He joined the Rockies under his current role in February 2021.
Olsonawski is still fairly new to that side of baseball, having been in it for five years. It's an opportunity to learn from someone who's been in his shoes before.
"I think the core principles are the same. It's just how different the message can be delivered. At the end of the day, we're just trying to get our pitchers to get dudes out.
"You want to limit walks, get swing-and-miss. But also starters, the value is in pitching deep in the game, not walking guys and getting outs. So at the end of the day, that's the core root of everything."
Drey Jameson Makes Encouraging Progress in the Arizona Fall League
As arguably the most important player from the D-backs' AFL content, Drey Jameson should have an inside track to make the club next spring. He's coming off a third season marred by elbow issues, which include Tommy John surgery, rehab complications, and bone spurs.
Speaking to Steve Gilbert, who covers the D-backs for MLB.com, Jameson revealed he took Botox shots to alleviate the elbow pain after everything else failed. The right-hander got a shot in the neck and shoulder.
It's safe to say the treatment has proven successful so far. In five of his six outings, Jameson is averaging over 98 MPH on his four-seam fastball. The velocity is back; now it's just a question of getting his confidence and complete stuff back.
"Yeah, I think we're getting there. He was down for a little bit this year. For me, the big thing is getting that confidence back in him. That's Drey's number one weapon, attacking with his confidence. And when he has confidence in his stuff, he's gonna be electric."
Olsonawski has worked with Jameson for the past four seasons. Their relationship began during their time together at Triple-A Reno in 2022. Olsonawski was doing video work with Reno as part of player development, and Jameson was fast-charging toward a big league debut.
"Drey's been fun to work with. I've worked with him for parts of four years now, developed a good relationship with him. At the end of the day, it's nice to be able to reflect back on the different cues, different things we've tried out three, four years ago now. So it's good to have that kind of foundation and that circle of trust that we have with each other."
If Jameson can be healthy in 2026, the combination of velocity, secondary stuff, and competitiveness he brings to the mound will make him a weapon out of the bullpen.
David Hagaman's Curious Velocity Drop
One thing I noticed watching David Hagaman pitch the last two weeks was his velocity drop when holding runners on first.
Multiple potential factors could be causing that. The extra wear-and-tear of going from rehab to pitching, followed by a one-month layoff, and then ramping back up again.
"I think for him too, it's just getting back. Getting back to his strengths. It's been a long season coming back from [internal brace surgery] with him, and he's at about 45 innings now on the year coming off [surgery].
"Pitching in late October, it's different. The body's different. It's been a taxing season for him. Right now, we're just working on getting his confidence back and getting him back to who he is as a pitcher.
Biomechanics and Pitch Shaping
Right now, the newest frontier for pitching development comes down to how organizations can use biomechanical data to optimize arsenals. The D-backs are one of many teams that are aggressive in that area, as noted by their pitching development lab at their Spring Training Complex.
As one of the pitching coaches at that level, Olsonawski is no stranger to the pitching lab.
"That's been kind of one of the benefits of being at the complex last two years. We have a pitching lab in-house. It's definitely been something that I've been exposed to the last two seasons, kind of have a solid foundation and base of that."
Two relievers that came up in 2025 carry unique fastball shapes. Taylor Rashi and Philip Abner both feature four-seamers that naturally cut to the glove side of the plate. Both pitchers sit around 90 MPH with their fastball, so the shape should give hitters a new wrinkle to handle.
"Both those guys, it was definitely an acquisition side where you identify an outlier's trait in the guy's primary pitch, and you lean into it. Abner, he's always had that four-seam that cut. And I think the big thing, again, like we talked in the past, but you lean into those pitches with those guys. And you get them to trust it, and trust that it's gonna work level by level as you keep going up.
"Rashi's kind of always had that same too, high over the slot guy, gets on the side of the baseball, and he's able to rip it, and he throws it with confidence and attacks."
Another pitch was recently added that could play a role in the D-backs' 2026 bullpen is Yordin Chalas' splitter. Chalas has only thrown seven splitters in Arizona out of 84 total pitches, relying more on his sinker and slider combination.
"Chalas, that was one of the things we were looking at. How can we add a third pitch to the mix? With him, it was just something that a lot of thought goes into it behind the scenes.
"You have a couple different options for grips. And you just see which one clicks and which one works for him. Right away, we put that one in his hand last year. I think at the end of bridge camp, we sent him back, and he picked up on it right away. And it's really kind of developed into one of his weapons."
The right-hander has looked good in the AFL, pitching 5.2 scoreless innings with a 7/1 strikeout-to-walk ratio. His only blemish was yielding a bases-clearing double to Cutter Coffey, allowing three inherited runners to score in a loss to Glendale.