22% CUP. ECD April 16. The Phillies’ top prospect has not played a game in 2026 due to a recurring lower back issue. He just started swinging a bat. The April window has elapsed. The question is whether he can get healthy in time for the June 18 calibration checkpoint.
The model assigned Miller a 22% CUP on March 20 with an ECD of April 16 via Pathway A. That window has passed without a promotion. Miller has not played a game in 2026. He began spring training with a recurring lower back issue, did not appear in a single Grapefruit League game, and is currently on the 7-day injured list with Triple-A Lehigh Valley. As of April 9, he has just started swinging a bat again. There is no timeline for his return to game action.
Miller was selected by Philadelphia with the 27th overall pick in the 2023 draft out of Mitchell High School in New Port Richey, Florida. He is 21 years old. In two professional seasons, he has hit his way through three levels faster than almost any position prospect in the organization. In 2024, across High-A and Double-A, he slashed .261/.366/.446 with 11 home runs and 23 stolen bases. In 2025, between Double-A Reading and Triple-A Lehigh Valley, he batted .264 with 27 doubles, 14 home runs, 59 stolen bases, and an .825 OPS across 116 games. His 185 wRC+ in eight Triple-A games that September was a brief look at what comes next.
Miller plays shortstop and has not played anywhere else in his professional career. The Phillies invited him to big-league camp this spring as a non-roster invitee with the expectation he would get work at third base and second base alongside Turner, Stott, and Bohm, building toward a midseason call-up. The back issue ended that plan before it started.
Miller experienced lower back soreness late in the 2025 minor league season, enough to scratch him from the Arizona Fall League. The Phillies described it as nagging soreness and said he arrived at spring training healthy. On February 21, just before Philadelphia’s first Grapefruit League game, he reported soreness in his lower back and was shut down. He flew to Philadelphia in early March for further evaluation. He did not participate in spring training at all.
Miller told reporters there was no specific incident that caused it. “Structurally, there’s nothing wrong there,” he said. “It’s just, I think swinging a bat 100,000 times a year, we put a little bit of a toll on it.” Phillies president of baseball operations Dave Dombrowski confirmed on April 9 that Miller has started swinging a bat again, calling it “the next step in his progress.” Dombrowski declined to give a timetable and declined to say whether Miller received any injection therapy, citing HIPAA. “You don’t want to push him too fast,” Dombrowski said.
Miller’s call-up path runs through the Philadelphia infield. Trea Turner is signed through 2033. Bryson Stott is established at second base. Alec Bohm, the third baseman, is in his final year of team control and becomes a free agent after 2026. That opening at third base is the most likely landing spot for Miller when he arrives. The model assigned him a Medium PPI status. His back issue has already cost him April. A realistic timeline now looks like June at the earliest, assuming he returns to game action in the next two to three weeks and gets sufficient Triple-A at-bats before the Phillies decide he is ready.
The model scored Miller at CUS 56 and 22% CUP with an ECD of April 16 and a High confidence rating on March 20. The April window has elapsed without a promotion or return to game action. The 90-day window closes June 18 at the calibration checkpoint. If Miller cannot get healthy and accumulate Triple-A at-bats before then, the 22% probability resolves to zero. The back injury was flagged in the original brief as the primary suppressor. It remains the primary suppressor.