On Sept. 1, all players on a team’s 40-man roster will be eligible to play in the big leagues without an accompanying move. Often times, baseball fans are treated to a sneak preview of teams’ top minor league talent as a result of September call-ups; or they’re surprised by a relatively unknown player who manages to contribute over the season’s final month.

In preparation for this year’s roster expansion, I thought it would be interesting to look back at the greatest-ever September call-ups, defined here as players that made their major league debut during the month of September.

Read the whole story at FanGraphs