September roster expansion is almost here, and for the first time in memory, calling up a top prospect might cost a team more than it gains them. That’s the calculation playing out quietly — and in some cases not so quietly — across MLB front offices right now.
The issue, first reported by @SmittyOnMLB on August 20, comes down to one rule: to reach the majors, a player must be added to the 40-man roster. And any player on the 40-man roster when the current CBA expires is locked out — frozen from team contact, spring training, and even minor league games if the 2027 season gets canceled.
How the Lockout Mechanic Works
The collective bargaining agreement between MLB and the MLBPA expires at 11:59 p.m. ET on December 1, 2026. A lockout — which both sides essentially treat as a given — would immediately cut off all communication between clubs and any player on their 40-man roster.
That means a prospect called up in September would spend the lockout in limbo: no workouts with the organization, no spring training, and no minor league games if MLB play gets pushed back in 2027. A player left off the 40-man, on the other hand, isn’t subject to the lockout at all. He can keep developing in the minors throughout the entire work stoppage.
For a 20-year-old in the middle of his prime developmental window, that difference in repetitions isn’t trivial.
MLBPA interim executive director Bruce Meyer was blunt about the outlook back in March 2026, stating that «the league has essentially already said there will be a lockout.» With owners pushing a salary cap for the first time since 1994 — a position the union flatly rejects — analysts expect this work stoppage to be longer and more contentious than the 99-day lockout of 2021-22.
The Prospects Caught in the Middle
The timing couldn’t be worse for some of the best young players in the game. According to Kiley McDaniel’s updated ESPN rankings (August 2026), the top of the prospect list is loaded with players who are close to ready but now have a concrete reason to stay put:
- Jesús Made, 19-year-old SS, Milwaukee Brewers (Double-A) — ranked #1 overall in baseball
- Franklin Arias, Boston Red Sox — ranked #2, up from #36 earlier this season, posting an EV90 of 105.0 mph with hard contact on more than 50% of his batted balls
- Kade Anderson, Seattle Mariners (LHP, Double-A) — #3
- Leo De Vries, Oakland Athletics (SS) — #4
All four are legitimate callup candidates on merit. All four carry lockout risk if they’re added to a 40-man roster before December 1.
The most striking individual case is Seth Hernández, the right-handed starter for the Pittsburgh Pirates currently in High-A. In 2026 he’s posted a 0.82 ERA with 57 strikeouts and just 13 hits allowed in 33.0 innings. In any other year, the only question would be when he arrives, not whether. This year, Pittsburgh has to ask whether bringing him up now is actually worth it.
Miami Is Already Adjusting
The Miami Marlins are the clearest public example of how this calculus is changing behavior. According to Fish On First, the organization is actively considering holding back prospects not currently on the 40-man roster in order to preserve their minor league eligibility during a lockout. They’re not the only team thinking this way — just the first one to have it become public.
What Doesn’t Change
One thing worth clarifying: any player called up with fewer than 45 days remaining in the regular season does not lose their prospect eligibility under current rules. That concern circulated on social media and it’s not the real issue. The real issue is development time lost during a work stoppage, not eligibility status.
For the 2027 season to open on time, both sides would need a deal in place around March 2027. Sportico notes that if negotiations are progressing in December, MLB could potentially delay the lockout — but neither side has shown meaningful flexibility, particularly on the salary cap question.
September expansion bumps active rosters from 26 to 28 players (with a 14-pitcher maximum). That’s two extra spots per team. In past years, those spots were a low-risk way to give a top prospect their first taste of the big leagues. In 2026, that taste comes with a price tag nobody budgeted for.
