MLB Pipeline published a piece identifying possible breakout prospects from all 30 organizations. For the Arizona Diamondbacks, they picked right-hander David Hagaman, who’s in the center of their graphic.
Hagaman, 22, was part of the return the Diamondbacks got from the Texas Rangers in the Merrill Kelly trade. The deal also included left-handers Mitch Bratt and Kohl Drake, both of whom are on Arizona’s current 40-man roster. He’s currently ranked as the Diamondbacks’ No. 15 prospect, although he may rise into the Top 10 when they redo them in the spring.
After the trade, Hagaman pitched for the club’s High-A affiliate in Hillsboro, going 1-0 with a 3.15 ERA. In 20 innings, he struck out 27 while walking only four. In his first year back from April 2024 elbow surgery, the right-hander pitched to a 2.98 ERA in 42.1 innings.
Following a strong finish to the season, the Diamondbacks sent him to the Arizona Fall League. He had some uneven results, as his command slipped in some of his starts, but showed a legit four-pitch mix. Hagaman projects as a mid-rotation starter, possibly more if the stuff ticks up in the future.
Why David Hagaman is a Breakout Candidate in 2026
Hagaman’s run with Hillsboro showed some very encouraging results. He had a 35.5% strikeout rate and a 5.3% walk rate in those 20 innings. He finished the Arizona Fall League, so he’ll have a normal offseason to prepare for the 2026 season.
In the Arizona Fall League, Hagaman sat mostly mid-90s on his four-seamer, topping out at 96.9 MPH. He generates over seven feet of extension, which creates a flatter angle on his fastball. He’ll utilize a curveball, slider, and a changeup as his secondaries. Baseball America rates his curveball as the best in their system over Daniel Eagen and Hayden Durke.
2026 shapes up to be a huge year for Hagaman. With more than a full year recovered from elbow surgery (April 2024), the Diamondbacks should be able to turn him loose. He didn’t throw more than 69 pitches in a single start in 2025.
Hagaman likely begins the year with Hillsboro, but could be fast-tracked to Double-A Amarillo in 2026. For the Diamondbacks, the key will be to see how his stuff holds up 60+ pitches in and what his overall command looks like. A good year for Hagaman could finish with him getting a cup of coffee with Triple-A Reno.
MLB Pipeline projects his ETA as 2027. At full strength, he’s unlikely to crack the rotation that spring, but could be a midseason call-up candidate.
The Diamondbacks’ Starting Pitching Pipeline
The Diamondbacks entered the 2025 trade deadline with a weak starting pitching pipeline. Their best pitching prospect was Daniel Eagen, who was having an outstanding first year in the system. Outside of him, the system lacked much impact.
The Kelly and Josh Naylor deals landed the team four plausible starting pitcher candidates. The Naylor trade to Seattle landed two pitchers with a bright future in Arizona, Brandyn Garcia and Ashton Izzi. Izzi will join Eagen in Amarillo, with Hagaman not too far behind.
The Diamondbacks need to be able to develop starters from their farm system. Ryne Nelson still serves as the most successful example, followed by Brandon Pfaadt. They made a key hire in the offseason, landing former Pirates exec Jeremy Bleich. Bleich oversaw the development of Paul Skenes, Bubba Chandler, and other high-impact starters.
The quartet of Drake, Eagen, Hagaman, and Izzi will be the first wave of pitchers coming up the system. How those four pitchers fare in Arizona could determine how quickly their next window of contention opens up.
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