A bullpen game is a game a team pitches entirely with relievers, with no starter or bulk pitcher expected to go deep. Each reliever covers one to three innings, matched to the part of the lineup he handles best. Teams turn to bullpen games when the rotation is thin, when a starter is hurt, or in the playoffs when off days let relievers work more often. Both the Astros and White Sox opened the 2026 AL Wild Card Series with bullpen games on Tuesday, September 29: AJ Blubaugh opened for Houston, which used its top starters to clinch the division on the final weekend, and rookie Hagen Smith opened for Chicago, whose bullpen led MLB in innings this season.
How a Bullpen Game Is Built
| Innings | Typical role |
|---|---|
| 1 to 2 | Opener, chosen to face the top of the order |
| 3 to 5 | Long reliever or swingman, the closest thing to a bulk pitcher |
| 6 to 7 | Middle relievers, often split by matchup against left and right handed hitters |
| 8 to 9 | Setup man and closer, as in any game |
Why Teams Do It
Relievers throw harder and use their best pitch more often than starters because they only need to get three to nine outs, so a deep bullpen can hold a lineup down for nine innings if no one gets exposed a second time through. In the postseason the calculus changes further: there are off days, so relievers can pitch three days in four, and a team would rather use eight relievers than send a fifth starter out against a playoff lineup. The risk is the next day, when the bullpen is spent and the following starter has no safety net.
Bullpen Game vs. Opener
An opener is a single reliever who starts before a bulk pitcher takes over for most of the game; a bullpen game has no bulk pitcher at all. Openers protect a starter, bullpen games replace one. The Phillies used an opener in Game 1 (Jesus Luzardo ahead of Andrew Painter), while Houston and Chicago went with full bullpen games.
Related
What is an opener · White Sox vs. Astros series · Wild Card lineups · MLB playoff rules
Roster and pitching rules are from MLB.com.