A September call-up is a player added to a major league team's roster after September 1st, which has traditionally been the date after which teams can play with an expanded roster. Until 2022, the only limit to the number of such call-ups was that they had to be on the team's 40-man roster, but that year, following long-standing complaints that having a large number of additional players on the roster for the final month of the season changed the nature of the game, such call-ups were limited to only two players - at least one of which must be a position player.
The date was chosen because the seasons of minor league teams end around that date, making players not involved in their league's postseason available. It was traditionally a time to give young prospects a first taste of the major leagues, or role players a chance to help out in a pennant race: for example a number of players saw their first or only action as pinch-runner during a September call-up. In the case of prospects, this has changed, as considerations linked to service time, managing workload (especially for pitchers) and so forth are now paramount.
Because they join the team after September 1st, call-ups are not normally eligible for postseason play, although teams have found ways around this in the past when a player has been particularly impressive during his cup of coffee. Most famously, the Anaheim Angels used roster manipulations to add reliever Francisco Rodriguez to their postseason roster after an impressive September call-up in 2002, and he became a key contributor towards the first World Series win in franchise history.
- "Every team's best September callup", mlb.com, August 31, 2022. 
We're Social...for Statheads
Every Sports Reference Social Media Account
Site Last Updated:
Question, Comment, Feedback, or Correction?
Subscribe to our Free Email Newsletter
This Month in Sports Reference
Find out when we add a feature or make a change
Do you have a sports website? Or write about sports? We have tools and resources that can help you use sports data. Find out more.