The San Diego Padres acquired closer Mason Miller from the A’s at the trade deadline. They gave up a lot in order to secure the high leverage reliever and a starter, JP Sears, from the A’s. Sears is a back-of-the-rotation innings eater, who had a start that showed how volatile he can be before being sent down to El Paso.

Miller, 26 years old, is a 2024 All-Star, who has high velocity on his fastball that has earned him notoriety from the best in baseball . He also has a wicked slider that moves away from right-handed hitters. But Miller has not always been a reliever. In fact, for the majority of his pitching career, he was a starter. It has been brought up among fans that the Padres have a pretty good history of converting relievers to starters (Michael Wacha, Seth Lugo, Michael King) and Miller could be the next success story on that list.

In Miller’s five-year college career he was diagnosed with Type I Diabetes in his sophomore season at Waynesburg University (Pennsylvania). After missing time due to his illness, he completed his four-year degree and transferred to Gardner-Webb University (North Carolina) for a fifth year. For all of his college career, Miller was primarily a starter. Over the five years, he threw 239 innings with a 3.92 ERA in 38 games started and 50 games overall. He had 3 saves during his college career.

Drafted by the Oakland A’s in 2021, Miller moved quickly through the minor leagues. He pitched a total of 39.1 innings from 2021 through his April 19, 2023 debut with the A’s. In his first start with Oakland, he threw 15 pitches at greater than 100 mph. By May, after just a handful of starts, Miller went on the IL with a UCL sprain and was transferred to the 60-day IL in June. He did not return to the team until Sept. 6, throwing out of the bullpen for the rest of the season.

Before the 2024 season, A’s general manager David Forst indicated that Miller would remain in the bullpen for that entire season due to injury concerns. For the season, Miller threw 65 innings with a 2.49 ERA and 104 strikeouts. His fastball averaged 101 mph and was used 63% of the time. He also threw his slider at 87 mph 35% of the time. He used his changeup sparingly, 2% at 92 mph.

The high-leverage reliever was chosen for his first All-Star game as a reserve and after the season, the discussion about returning him to the rotation was brought up with the A’s. Forst expressed that they would not be toying with success. Miller would remain a reliever.

Fast forward to August 2025, Miller is a member of the Padres bullpen after a blockbuster trade with the A’s. He compliments an already dominant Padres bullpen that is loaded and ready for a playoff run. Of course, changing his role is not an option at this point.

Miller has 434.2 innings pitched through his college and pro careers due to his fast advance through the minor leagues. He is a max effort pitcher with two pitches that he throws 98% of the time. His fastball has topped out at 104 mph and his slider sits in the high 80’s. He uses his changeup sparingly.

Padres pitching coach Ruben Niebla, AKA the pitching whisperer, has a reputation for being one of the best in baseball. He has a biomechanics lab that has already demonstrated the ability to greatly enhance pitchers’ ability. Miller is under control for the next four seasons, a perfect opportunity for the organization to do a deep dive into Miller’s mechanics, pitch development and pitch use in order to entertain a move to the rotation. But the past history of a UCL sprain would dictate that Miller be handled with care. His max effort pitching could be scaled back in a starter scenario, allowing him to use the high heat sparingly. For that to work he would need to develop/refine his pitch mix and delivery.

This debate will probably be on the back burner for the rest of this season, but expect to hear a lot more after the season and before next spring training. Dreaming on what Miller could do in the starting rotation is a fascinating and seductive discussion. But blowing out his elbow would not help the Padres and deciding which course to take will be a real point of interest for all of us.