Pirates September Call-Ups: The Auditions That Actually Matter

SWN Analysis · August 26, 2026

Rosters expand from 26 to 28 on Sept. 1. Records current as of Aug. 26, 2026.

Pittsburgh is 65-69 and won’t be playing in October. That changes what September is for.

For a contender, roster expansion is about adding arms to survive a race. For the Pirates, it’s an audition month — a chance to find out which of the eight top-30 prospects who started the year at Triple-A Indianapolis belong in the 2027 plan.

That’s not a consolation prize. It’s the most consequential thing this organization does between now and spring training.

The headliner is already here

Konnor Griffin didn’t wait for September, or for much of anything.

The ninth overall pick in 2024 and the consensus No. 1 prospect in baseball opened 2026 at Indianapolis, played five games, and was promoted to Pittsburgh — then signed a nine-year, $140 million extension a couple of weeks before his 20th birthday.

That’s an extraordinary bet on a player with almost no major league track record, and the early returns justified it. After initially struggling with the quality of big league stuff, Griffin turned a corner in mid-May and was slashing .317/.359/.433 over his last 15 games before a flexor strain sent him to the injured list.

The scouting notes on him read like something from another sport. At a muscular 6-foot-3, the added strength let him shorten his swing and drive minor league fastballs to his pull side with real regularity — a skill that hasn’t fully translated against major league velocity yet.

He also won a minor league Gold Glove at shortstop. In 2025, across three levels, he hit .333 with a .941 OPS, 94 RBI and 65 stolen bases.

What September means for him: health, and reps against big league fastballs. Nothing else.

Termarr Johnson, 2B/SS — Triple-A Indianapolis

The fourth overall pick in 2022, and Griffin’s double-play partner at Indianapolis.

Johnson moved up to Triple-A after a solid 2025 at Double-A Altoona: .272 with a .745 OPS (118 OPS+), nine home runs, 35 RBI and a second straight 20-steal season.

The detail worth knowing: he drastically improved against left-handed pitching, finishing at .314 with a .782 OPS against southpaws. For a young left-handed hitter, closing that gap is the difference between a platoon player and an everyday one.

He has also consistently been among the youngest players in every league he’s played in.

Projection: a strong candidate for a September look, with 2027 playing time as the real question.

Ronny Simon, IF/OF — Triple-A Indianapolis

The most productive hitter at Indianapolis this season and the least famous name on this list.

Simon was named the club’s hitter of the month for April with a 1.047 OPS and has hit .327/.411/.487 (138 wRC+) with extra-base power and stolen bases. The batted-ball data backs it up: a 91.8 mph average exit velocity and a 45.7% hard-hit rate, both in the top quartile among qualified Triple-A hitters.

He plays second base, shortstop, left field and right field.

The obstacle: roster crunch. With Jared Triolo and Jake Mangum healthy and Esmerlyn Valdez and Jhostynxon García already promoted, there hasn’t been an obvious opening. Triolo hasn’t played second base this year, though, which is Simon’s primary position.

The argument: if Don Kelly wants to keep Brandon Lowe fresh down the stretch, Indianapolis’ best hitter is the obvious place to find those innings.

The pitching auditions

Bubba Chandler is the organization’s top pitching prospect and the arm whose development matters most to the 2027 rotation.

Hunter Barco, a top-100 left-hander, made the big league bullpen out of spring training and was optioned back to Indianapolis in April after a rough four appearances. A September return would let him finish the year on a better note than he started it.

Khristian Curtis had his contract selected from Indianapolis in July and is the kind of arm September is designed to evaluate.

Why the farm system depth matters

Pittsburgh opened this season with eight top-30 prospects at Triple-A Indianapolis — six of them in the organization’s top ten.

That kind of logjam at the highest minor league level is exactly what a rebuilding front office wants. It gives the major league club options, it pressures the players already up, and it produces trade currency for whenever this team decides it’s ready to add rather than accumulate.

Six weeks of September at-bats is how you find out which category each of them falls into.

What to actually watch

• Griffin’s health. A flexor strain in a 20-year-old with a nine-year contract is the only thing on this list that genuinely matters.
• Johnson against left-handed pitching. The Double-A improvement has to travel.
• Whether Simon gets a look at all. The roster math says no; the production says he’s earned it.
• How many stick. The measure of this September isn’t wins — it’s how many of these names are on the Opening Day roster in 2027.

The Pirates aren’t playing for anything in the standings. They’re playing for next year’s lineup card, which for a team in this position is the more useful thing to be playing for.

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